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class="vector-menu-content-list"> </ul> </div> </div> <div id="p-vector-user-menu-overflow" class="vector-menu mw-portlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-sitesupport-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="https://donate.wikimedia.org/wiki/Special:FundraiserRedirector?utm_source=donate&utm_medium=sidebar&utm_campaign=C13_en.wikipedia.org&uselang=en" class=""><span>Donate</span></a> </li> <li id="pt-createaccount-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:CreateAccount&returnto=Copyleft" title="You are encouraged to create an account and log in; however, it is not mandatory" class=""><span>Create account</span></a> </li> <li id="pt-login-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" 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class="vector-sitenotice-container"> <div id="siteNotice"></div> </div> <div class="vector-column-start"> <div class="vector-main-menu-container"> <div id="mw-navigation"> <nav id="mw-panel" class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-pinned-container" class="vector-pinned-container"> </div> </nav> </div> </div> <div class="vector-sticky-pinned-container"> <nav id="mw-panel-toc" aria-label="Contents" data-event-name="ui.sidebar-toc" class="mw-table-of-contents-container vector-toc-landmark"> <div id="vector-toc-pinned-container" class="vector-pinned-container"> <div id="vector-toc" class="vector-toc vector-pinnable-element"> <div class="vector-pinnable-header vector-toc-pinnable-header vector-pinnable-header-pinned" data-feature-name="toc-pinned" data-pinnable-element-id="vector-toc" > <h2 class="vector-pinnable-header-label">Contents</h2> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-toc.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">hide</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">(Top)</div> </a> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>History</span> </div> </a> <ul id="toc-History-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Copyleft_principles" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Copyleft_principles"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Copyleft principles</span> </div> </a> <button aria-controls="toc-Copyleft_principles-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Copyleft principles subsection</span> </button> <ul id="toc-Copyleft_principles-sublist" class="vector-toc-list"> <li id="toc-Freedom" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Freedom"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>Freedom</span> </div> </a> <ul id="toc-Freedom-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Reciprocity" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Reciprocity"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Reciprocity</span> </div> </a> <ul id="toc-Reciprocity-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Economic_incentive" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Economic_incentive"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.3</span> <span>Economic incentive</span> </div> </a> <ul id="toc-Economic_incentive-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Copyleft_application" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Copyleft_application"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Copyleft application</span> </div> </a> <ul id="toc-Copyleft_application-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Types_and_relation_to_other_licenses" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Types_and_relation_to_other_licenses"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Types and relation to other licenses</span> </div> </a> <button aria-controls="toc-Types_and_relation_to_other_licenses-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Types and relation to other licenses subsection</span> </button> <ul id="toc-Types_and_relation_to_other_licenses-sublist" class="vector-toc-list"> <li id="toc-Strong_and_weak_copyleft" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Strong_and_weak_copyleft"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Strong and weak copyleft</span> </div> </a> <ul id="toc-Strong_and_weak_copyleft-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Full_and_partial_copyleft" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Full_and_partial_copyleft"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>Full and partial copyleft</span> </div> </a> <ul id="toc-Full_and_partial_copyleft-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Share-alike" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Share-alike"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.3</span> <span>Share-alike</span> </div> </a> <ul id="toc-Share-alike-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Permissive_licenses" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Permissive_licenses"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.4</span> <span>Permissive licenses</span> </div> </a> <ul id="toc-Permissive_licenses-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Debate_and_controversy" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Debate_and_controversy"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Debate and controversy</span> </div> </a> <button aria-controls="toc-Debate_and_controversy-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Debate and controversy subsection</span> </button> <ul id="toc-Debate_and_controversy-sublist" class="vector-toc-list"> <li id="toc-"Viral"_licensing" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#"Viral"_licensing"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>"Viral" licensing</span> </div> </a> <ul id="toc-"Viral"_licensing-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Symbol" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Symbol"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Symbol</span> </div> </a> <button aria-controls="toc-Symbol-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Symbol subsection</span> </button> <ul id="toc-Symbol-sublist" class="vector-toc-list"> <li id="toc-Typing_the_character" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Typing_the_character"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.1</span> <span>Typing the character</span> </div> </a> <ul id="toc-Typing_the_character-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Copyleft</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 62 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-62" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">62 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/Kopielinks" title="Kopielinks – Afrikaans" lang="af" hreflang="af" data-title="Kopielinks" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-als mw-list-item"><a href="https://als.wikipedia.org/wiki/Copyleft" title="Copyleft – Alemannic" lang="gsw" hreflang="gsw" data-title="Copyleft" data-language-autonym="Alemannisch" data-language-local-name="Alemannic" class="interlanguage-link-target"><span>Alemannisch</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AD%D9%82%D9%88%D9%82_%D9%85%D8%AA%D8%B1%D9%88%D9%83%D8%A9" title="حقوق متروكة – Arabic" lang="ar" hreflang="ar" data-title="حقوق متروكة" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/Copyleft" title="Copyleft – Asturian" lang="ast" hreflang="ast" data-title="Copyleft" data-language-autonym="Asturianu" data-language-local-name="Asturian" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/Kopileft" title="Kopileft – Azerbaijani" lang="az" hreflang="az" data-title="Kopileft" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%92%D0%BE%D0%BB%D1%8C%D0%BD%D0%B0%D0%B5_%D0%B0%D1%9E%D1%82%D0%B0%D1%80%D1%81%D0%BA%D0%B0%D0%B5_%D0%BF%D1%80%D0%B0%D0%B2%D0%B0" title="Вольнае аўтарскае права – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Вольнае аўтарскае права" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/Copyleft" title="Copyleft – Bulgarian" lang="bg" hreflang="bg" data-title="Copyleft" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Copyleft" title="Copyleft – Catalan" lang="ca" hreflang="ca" data-title="Copyleft" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Copyleft" title="Copyleft – Czech" lang="cs" hreflang="cs" data-title="Copyleft" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Copyleft" title="Copyleft – Danish" lang="da" hreflang="da" data-title="Copyleft" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Copyleft" title="Copyleft – German" lang="de" hreflang="de" data-title="Copyleft" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Copyleft" title="Copyleft – Estonian" lang="et" hreflang="et" data-title="Copyleft" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/Copyleft" title="Copyleft – Greek" lang="el" hreflang="el" data-title="Copyleft" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Copyleft" title="Copyleft – Spanish" lang="es" hreflang="es" data-title="Copyleft" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Rajtocedo" title="Rajtocedo – Esperanto" lang="eo" hreflang="eo" data-title="Rajtocedo" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Copyleft" title="Copyleft – Basque" lang="eu" hreflang="eu" data-title="Copyleft" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%DA%A9%D9%BE%DB%8C%E2%80%8C%D9%84%D9%81%D8%AA" title="کپی‌لفت – Persian" lang="fa" hreflang="fa" data-title="کپی‌لفت" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Copyleft" title="Copyleft – French" lang="fr" hreflang="fr" data-title="Copyleft" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Copyleft" title="Copyleft – Galician" lang="gl" hreflang="gl" data-title="Copyleft" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%B9%B4%ED%94%BC%EB%A0%88%ED%94%84%ED%8A%B8" title="카피레프트 – Korean" lang="ko" hreflang="ko" data-title="카피레프트" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%94%D5%B8%D6%83%D5%AB%D5%AC%D5%A5%D6%86%D5%A9" title="Քոփիլեֆթ – Armenian" lang="hy" hreflang="hy" data-title="Քոփիլեֆթ" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%95%E0%A5%89%E0%A4%AA%E0%A5%80%E0%A4%B2%E0%A5%87%E0%A4%AB%E0%A5%8D%E0%A4%9F" title="कॉपीलेफ्ट – Hindi" lang="hi" hreflang="hi" data-title="कॉपीलेफ्ट" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Copyleft" title="Copyleft – Croatian" lang="hr" hreflang="hr" data-title="Copyleft" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Copyleft" title="Copyleft – Indonesian" lang="id" hreflang="id" data-title="Copyleft" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-ia mw-list-item"><a href="https://ia.wikipedia.org/wiki/Copyleft" title="Copyleft – Interlingua" lang="ia" hreflang="ia" data-title="Copyleft" data-language-autonym="Interlingua" data-language-local-name="Interlingua" class="interlanguage-link-target"><span>Interlingua</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/H%C3%B6fundarrangur" title="Höfundarrangur – Icelandic" lang="is" hreflang="is" data-title="Höfundarrangur" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Copyleft" title="Copyleft – Italian" lang="it" hreflang="it" data-title="Copyleft" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/Copyleft" title="Copyleft – Hebrew" lang="he" hreflang="he" data-title="Copyleft" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-ku mw-list-item"><a href="https://ku.wikipedia.org/wiki/Copyleft" title="Copyleft – Kurdish" lang="ku" hreflang="ku" data-title="Copyleft" data-language-autonym="Kurdî" data-language-local-name="Kurdish" class="interlanguage-link-target"><span>Kurdî</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/Copyleft" title="Copyleft – Latin" lang="la" hreflang="la" data-title="Copyleft" data-language-autonym="Latina" data-language-local-name="Latin" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Copyleft" title="Copyleft – Latvian" lang="lv" hreflang="lv" data-title="Copyleft" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Copyleft" title="Copyleft – Lithuanian" lang="lt" hreflang="lt" data-title="Copyleft" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-lmo mw-list-item"><a href="https://lmo.wikipedia.org/wiki/Copyleft" title="Copyleft – Lombard" lang="lmo" hreflang="lmo" data-title="Copyleft" data-language-autonym="Lombard" data-language-local-name="Lombard" class="interlanguage-link-target"><span>Lombard</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Copyleft" title="Copyleft – Hungarian" lang="hu" hreflang="hu" data-title="Copyleft" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BF%D0%B8%D0%BB%D0%B5%D1%84%D1%82" title="Копилефт – Macedonian" lang="mk" hreflang="mk" data-title="Копилефт" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%AA%E0%B4%95%E0%B5%BC%E0%B4%AA%E0%B5%8D%E0%B4%AA%E0%B5%81%E0%B4%AA%E0%B5%87%E0%B4%95%E0%B5%8D%E0%B4%B7" title="പകർപ്പുപേക്ഷ – Malayalam" lang="ml" hreflang="ml" data-title="പകർപ്പുപേക്ഷ" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Copyleft" title="Copyleft – Malay" lang="ms" hreflang="ms" data-title="Copyleft" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Copyleft" title="Copyleft – Dutch" lang="nl" hreflang="nl" data-title="Copyleft" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%82%B3%E3%83%94%E3%83%BC%E3%83%AC%E3%83%95%E3%83%88" title="コピーレフト – Japanese" lang="ja" hreflang="ja" data-title="コピーレフト" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Copyleft" title="Copyleft – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Copyleft" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Copyleft" title="Copyleft – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Copyleft" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-mhr mw-list-item"><a href="https://mhr.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BF%D0%B8%D0%BB%D0%B5%D1%84%D1%82" title="Копилефт – Eastern Mari" lang="mhr" hreflang="mhr" data-title="Копилефт" data-language-autonym="Олык марий" data-language-local-name="Eastern Mari" class="interlanguage-link-target"><span>Олык марий</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Copyleft" title="Copyleft – Polish" lang="pl" hreflang="pl" data-title="Copyleft" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Copyleft" title="Copyleft – Portuguese" lang="pt" hreflang="pt" data-title="Copyleft" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-kaa mw-list-item"><a href="https://kaa.wikipedia.org/wiki/Kopyleft" title="Kopyleft – Kara-Kalpak" lang="kaa" hreflang="kaa" data-title="Kopyleft" data-language-autonym="Qaraqalpaqsha" data-language-local-name="Kara-Kalpak" class="interlanguage-link-target"><span>Qaraqalpaqsha</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Copyleft" title="Copyleft – Romanian" lang="ro" hreflang="ro" data-title="Copyleft" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BF%D0%B8%D0%BB%D0%B5%D1%84%D1%82" title="Копилефт – Russian" lang="ru" hreflang="ru" data-title="Копилефт" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Copyleft" title="Copyleft – Simple English" lang="en-simple" hreflang="en-simple" data-title="Copyleft" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Copyleft" title="Copyleft – Slovak" lang="sk" hreflang="sk" data-title="Copyleft" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Svobodna_avtorska_pravica" title="Svobodna avtorska pravica – Slovenian" lang="sl" hreflang="sl" data-title="Svobodna avtorska pravica" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/Kopileft" title="Kopileft – Serbian" lang="sr" hreflang="sr" data-title="Kopileft" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Copyleft" title="Copyleft – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Copyleft" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Copyleft" title="Copyleft – Finnish" lang="fi" hreflang="fi" data-title="Copyleft" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Copyleft" title="Copyleft – Swedish" lang="sv" hreflang="sv" data-title="Copyleft" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%85%E0%AE%B3%E0%AE%BF%E0%AE%AA%E0%AF%8D%E0%AE%AA%E0%AF%81%E0%AE%B0%E0%AE%BF%E0%AE%AE%E0%AF%88" title="அளிப்புரிமை – Tamil" lang="ta" hreflang="ta" data-title="அளிப்புரிமை" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-te mw-list-item"><a href="https://te.wikipedia.org/wiki/%E0%B0%95%E0%B0%BE%E0%B0%AA%E0%B1%80_%E0%B0%B2%E0%B1%86%E0%B0%AB%E0%B1%8D%E0%B0%9F%E0%B1%8D" title="కాపీ లెఫ్ట్ – Telugu" lang="te" hreflang="te" data-title="కాపీ లెఫ్ట్" data-language-autonym="తెలుగు" data-language-local-name="Telugu" class="interlanguage-link-target"><span>తెలుగు</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B8%81%E0%B8%AD%E0%B8%9B%E0%B8%9B%E0%B8%B5%E0%B9%80%E0%B8%A5%E0%B8%9F%E0%B8%95%E0%B9%8C" title="กอปปีเลฟต์ – Thai" lang="th" hreflang="th" data-title="กอปปีเลฟต์" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Copyleft" title="Copyleft – Turkish" lang="tr" hreflang="tr" data-title="Copyleft" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BF%D1%96%D0%BB%D0%B5%D1%84%D1%82" title="Копілефт – Ukrainian" lang="uk" hreflang="uk" data-title="Копілефт" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Copyleft" title="Copyleft – Vietnamese" lang="vi" hreflang="vi" data-title="Copyleft" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-wuu mw-list-item"><a href="https://wuu.wikipedia.org/wiki/Copyleft" title="Copyleft – Wu" lang="wuu" hreflang="wuu" data-title="Copyleft" data-language-autonym="吴语" data-language-local-name="Wu" class="interlanguage-link-target"><span>吴语</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/Copyleft" title="Copyleft – Chinese" lang="zh" hreflang="zh" data-title="Copyleft" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q133475#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav 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.mw-parser-output .sidebar:not(.notheme) .sidebar-list-title,html.skin-theme-clientpref-os .mw-parser-output .sidebar:not(.notheme) .sidebar-title-with-pretitle{background:transparent!important}html.skin-theme-clientpref-os .mw-parser-output .sidebar:not(.notheme) .sidebar-title-with-pretitle a{color:var(--color-progressive)!important}}@media print{body.ns-0 .mw-parser-output .sidebar{display:none!important}}</style><table class="sidebar nomobile nowraplinks hlist"><tbody><tr><th class="sidebar-title"><a href="/wiki/Intellectual_property" title="Intellectual property">Intellectual property</a></th></tr><tr><td class="sidebar-image"><span class="skin-invert-image" typeof="mw:File"><a href="/wiki/File:Intellectual_property_Noun_project.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Intellectual_property_Noun_project.svg/150px-Intellectual_property_Noun_project.svg.png" decoding="async" width="150" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Intellectual_property_Noun_project.svg/225px-Intellectual_property_Noun_project.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Intellectual_property_Noun_project.svg/300px-Intellectual_property_Noun_project.svg.png 2x" data-file-width="100" data-file-height="100" /></a></span></td></tr><tr><td class="sidebar-content"> <ul><li><a href="/wiki/Authors%27_rights" title="Authors' rights">Authors' rights</a></li> <li><a class="mw-selflink selflink">Copyleft</a></li> <li><a href="/wiki/Copyright" title="Copyright">Copyright</a></li> <li><a href="/wiki/Database_right" title="Database right">Database right</a></li> <li><a href="/wiki/Farmers%27_rights" class="mw-redirect" title="Farmers' rights">Farmers' rights</a></li> <li><a href="/wiki/Geographical_indication" title="Geographical indication">Geographical indication</a></li> <li><a href="/wiki/Indigenous_intellectual_property" title="Indigenous intellectual property">Indigenous intellectual property</a></li> <li><a href="/wiki/Industrial_design_right" title="Industrial design right">Industrial design right</a></li> <li><a href="/wiki/Integrated_circuit_layout_design_protection" title="Integrated circuit layout design protection">Integrated circuit layout design protection</a></li> <li><a href="/wiki/Moral_rights" title="Moral rights">Moral rights</a></li> <li><a href="/wiki/Patent" title="Patent">Patent</a></li> <li><a href="/wiki/United_Nations_Declaration_on_the_Rights_of_Peasants" title="United Nations Declaration on the Rights of Peasants">Peasants' rights</a></li> <li><a href="/wiki/Plant_breeders%27_rights" title="Plant breeders' rights">Plant breeders' rights</a></li> <li><a href="/wiki/Plant_genetic_resources" title="Plant genetic resources">Plant genetic resources</a></li> <li><a href="/wiki/Related_rights" title="Related rights">Related rights</a></li> <li><a href="/wiki/Supplementary_protection_certificate" title="Supplementary protection certificate">Supplementary protection certificate</a></li> <li><a href="/wiki/Trade_dress" title="Trade dress">Trade dress</a></li> <li><a href="/wiki/Trade_secret" title="Trade secret">Trade secret</a></li> <li><a href="/wiki/Trademark" title="Trademark">Trademark</a></li> <li><a href="/wiki/Utility_model" title="Utility model">Utility model</a></li></ul></td> </tr><tr><th class="sidebar-heading"> Related topics</th></tr><tr><td class="sidebar-content"> <ul><li><a href="/wiki/Abandonware" title="Abandonware">Abandonware</a></li> <li><a href="/wiki/Artificial_intelligence_and_copyright" title="Artificial intelligence and copyright">Artificial intelligence and copyright</a></li> <li><a href="/wiki/Brand_protection" title="Brand protection">Brand protection</a></li> <li><a href="/wiki/Copyright_abolition" title="Copyright abolition">Copyright abolition</a></li> <li><a href="/wiki/Copyright_troll" title="Copyright troll">Copyright troll</a></li> <li><a href="/wiki/Criticism_of_copyright" title="Criticism of copyright">Criticism of copyright</a></li> <li><a href="/wiki/Bioprospecting" title="Bioprospecting">Bioprospecting</a> <ul><li><a href="/wiki/Biopiracy" title="Biopiracy">Biopiracy</a></li></ul></li> <li><a href="/wiki/Idea%E2%80%93expression_distinction" title="Idea–expression distinction">Idea–expression distinction</a></li> <li><a href="/wiki/Limitations_and_exceptions_to_copyright" title="Limitations and exceptions to copyright">Limitations and exceptions to copyright</a> <ul><li><a href="/wiki/Fair_dealing" title="Fair dealing">Fair dealing</a></li> <li><a href="/wiki/Fair_use" title="Fair use">Fair use</a></li> <li><a href="/wiki/Paraphrasing_of_copyrighted_material" title="Paraphrasing of copyrighted material">Paraphrasing</a></li> <li><a href="/wiki/Right_to_quote" title="Right to quote">Right to quote</a></li></ul></li> <li><a href="/wiki/Orphan_work" title="Orphan work">Orphan work</a></li> <li><a href="/wiki/Patent_troll" title="Patent troll">Patent troll</a></li> <li><a href="/wiki/Pirate_Party" title="Pirate Party">Pirate Party</a></li> <li><a href="/wiki/Public_domain" title="Public domain">Public domain</a></li> <li><a href="/wiki/Outline_of_intellectual_property" title="Outline of intellectual property">Outline of intellectual property</a> <ul><li><a href="/wiki/Outline_of_patents" title="Outline of patents">Outline of patents</a></li></ul></li></ul> <hr /> <i>Higher categories:</i><br /><a href="/wiki/Property" title="Property">Property</a> and <a href="/wiki/Property_law" title="Property law">Property law</a></td> </tr><tr><td class="sidebar-navbar"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Intellectual_property" title="Template:Intellectual property"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Intellectual_property" title="Template talk:Intellectual property"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Intellectual_property" title="Special:EditPage/Template:Intellectual property"><abbr title="Edit this template">e</abbr></a></li></ul></div></td></tr></tbody></table> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1246091330"><table class="sidebar nomobile nowraplinks hlist"><tbody><tr><th class="sidebar-title"><a class="mw-selflink selflink">Copyleft</a></th></tr><tr><td class="sidebar-above"> Articles on copyleft licensing</td></tr><tr><th class="sidebar-heading"> Topics</th></tr><tr><td class="sidebar-content" style="padding-bottom:0.6em;"> <ul><li><a class="mw-selflink selflink">Copyleft</a></li> <li><a href="/wiki/Open-source_license" title="Open-source license">Open-source license</a></li> <li><a href="/wiki/Free-software_license" title="Free-software license">Free-software license</a></li> <li><a href="/wiki/Free_and_open-source_software" title="Free and open-source software">Free and open-source software</a></li> <li><a href="/wiki/Royalty-free" title="Royalty-free">Royalty-free</a></li></ul> <hr /> <p><i>Higher categories:</i> <a href="/wiki/Software" title="Software">Software</a>, <a href="/wiki/Freedom" title="Freedom">freedom</a> </p> <ul><li><a href="/wiki/Category:Free_and_open-source_software_licenses" title="Category:Free and open-source software licenses">Category:Free and open-source<br />software licenses</a></li></ul></td> </tr><tr><td class="sidebar-navbar"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Copyleft_sidebar" title="Template:Copyleft sidebar"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Copyleft_sidebar" title="Template talk:Copyleft sidebar"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Copyleft_sidebar" title="Special:EditPage/Template:Copyleft sidebar"><abbr title="Edit this template">e</abbr></a></li></ul></div></td></tr></tbody></table> <p><b>Copyleft</b> is the legal technique of granting certain freedoms over copies of <a href="/wiki/Copyright" title="Copyright">copyrighted</a> works with the requirement that the same rights be preserved in <a href="/wiki/Derivative_work" title="Derivative work">derivative works</a>. In this sense, <i>freedoms</i> refers to the use of the work for any purpose, and the ability to modify, copy, share, and redistribute the work, with or without a fee. <a href="/wiki/License" title="License">Licenses</a> which implement copyleft can be used to maintain copyright conditions for works ranging from <a href="/wiki/Computer_software" class="mw-redirect" title="Computer software">computer software</a>, to <a href="/wiki/Documents" class="mw-redirect" title="Documents">documents</a>, <a href="/wiki/Art" title="Art">art</a>, and scientific discoveries, and similar approaches have even been applied to <a href="/wiki/Patentleft" title="Patentleft">certain patents</a>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p><p>Copyleft <a href="/wiki/Software_license" title="Software license">software licenses</a> are considered <i>protective</i> or <i>reciprocal</i> in contrast with <a href="/wiki/Permissive_software_license" title="Permissive software license">permissive free software licenses</a>,<sup id="cite_ref-redhat2005_2-0" class="reference"><a href="#cite_note-redhat2005-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> and require that information necessary for reproducing and modifying the work must be made available to recipients of the software program, which are often distributed as <a href="/wiki/Executable" title="Executable">executables</a>. This information is most commonly in the form of <a href="/wiki/Source_code" title="Source code">source code</a> files, which usually contain a copy of the license terms and acknowledge the authors of the code. Copyleft helps ensure everyone's rights to freely use the product but it prohibits owning, registering copyright and earning royalties from copyright. </p><p>Notable copyleft licenses include the <a href="/wiki/GNU_General_Public_License" title="GNU General Public License">GNU General Public License</a> (GPL), originally written by <a href="/wiki/Richard_Stallman" title="Richard Stallman">Richard Stallman</a>, which was the first software copyleft license to see extensive use;<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup class="noprint Inline-Template noprint Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources" title="Wikipedia:No original research"><span title="This claim needs references to reliable secondary sources. (March 2024)">non-primary source needed</span></a></i>]</sup> the <a href="/wiki/Mozilla_Public_License" title="Mozilla Public License">Mozilla Public License</a>; the <a href="/wiki/Free_Art_License" title="Free Art License">Free Art License</a>;<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup class="noprint Inline-Template noprint Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources" title="Wikipedia:No original research"><span title="This claim needs references to reliable secondary sources. (March 2024)">non-primary source needed</span></a></i>]</sup> and the <a href="/wiki/Creative_Commons" title="Creative Commons">Creative Commons</a> <a href="/wiki/Share-alike" title="Share-alike">share-alike license condition</a><sup id="cite_ref-cc-by-sa_5-0" class="reference"><a href="#cite_note-cc-by-sa-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup class="noprint Inline-Template noprint Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources" title="Wikipedia:No original research"><span title="This claim needs references to reliable secondary sources. (March 2024)">non-primary source needed</span></a></i>]</sup>—with the last two being intended for non-software works, such as documents and pictures, both academic or artistic in nature. <a href="/wiki/Wikipedia" title="Wikipedia">Wikipedia</a> is copyleft under the <a href="/wiki/Creative_Commons_license" title="Creative Commons license">Creative Commons</a> Attribution-ShareAlike license. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Li-Chen_Wang" title="Li-Chen Wang">Li-Chen Wang</a>'s Palo Alto <a href="/wiki/Tiny_BASIC" title="Tiny BASIC">Tiny BASIC</a> for the <a href="/wiki/Intel_8080" title="Intel 8080">Intel 8080</a> appeared in <i><a href="/wiki/Dr._Dobb%27s_Journal" title="Dr. Dobb's Journal">Dr. Dobb's Journal</a></i> in May 1976. The listing begins with the title, author's name, and date, but also has "@COPYLEFT ALL WRONGS RESERVED".<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p><p>The concept of copyleft was described in <a href="/wiki/Richard_Stallman" title="Richard Stallman">Richard Stallman</a>'s <i><a href="/wiki/GNU_Manifesto" title="GNU Manifesto">GNU Manifesto</a></i> in 1985, where he wrote: </p> <style data-mw-deduplicate="TemplateStyles:r1244412712">.mw-parser-output .templatequote{overflow:hidden;margin:1em 0;padding:0 32px}.mw-parser-output .templatequotecite{line-height:1.5em;text-align:left;margin-top:0}@media(min-width:500px){.mw-parser-output .templatequotecite{padding-left:1.6em}}</style><blockquote class="templatequote"> <p>GNU is not in the public domain. Everyone will be permitted to modify and redistribute GNU, but no distributor will be allowed to restrict its further redistribution. That is to say, proprietary modifications will not be allowed. I want to make sure that all versions of GNU remain free. </p> </blockquote> <p>Stallman's motivation was that a few years earlier he had worked on a <a href="/wiki/Lisp_programming_language" class="mw-redirect" title="Lisp programming language">Lisp</a> interpreter. <a href="/wiki/Symbolics" title="Symbolics">Symbolics</a> asked to use the Lisp interpreter, and Stallman agreed to supply them with a <a href="/wiki/Public_domain_software" class="mw-redirect" title="Public domain software">public domain</a> version of his work. Symbolics extended and improved the Lisp interpreter, but when Stallman wanted access to the improvements that Symbolics had made to his interpreter, Symbolics refused. Stallman then, in 1984, proceeded to work towards eradicating this emerging behavior and culture of <a href="/wiki/Proprietary_software" title="Proprietary software">proprietary software</a>, which he named <i>software hoarding</i>. This was not the first time Stallman had dealt with proprietary software, but he deemed this interaction a "turning point". He justified software sharing, protesting that when sharing, the software online can be copied without the loss of the original piece of work. The software can be used multiple times without ever being damaged or worn out.<sup id="cite_ref-Carver_2005_7-0" class="reference"><a href="#cite_note-Carver_2005-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p><p>As Stallman deemed it impractical in the short term to eliminate current copyright law and the wrongs he perceived it to perpetuate, he decided to work within the framework of existing law; in 1985,<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> he created his own copyright license, the Emacs General Public License,<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> the first copyleft license. This later evolved into the <a href="/wiki/GNU_General_Public_License" title="GNU General Public License">GNU General Public License</a>, which is now one of the most popular free-software licenses. For the first time, a copyright holder had taken steps to ensure that the maximal number of rights be perpetually transferred to a program's users, no matter what subsequent revisions anyone made to the original program. This original GPL did not grant rights to the public at large, only those who had already received the program; but it was the best that could be done under existing law. </p><p>The new license was not at this time given the copyleft label.<sup id="cite_ref-autogenerated1_11-0" class="reference"><a href="#cite_note-autogenerated1-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Richard Stallman stated that the use of "Copyleft" comes from <a href="/wiki/Don_Hopkins" title="Don Hopkins">Don Hopkins</a>, who mailed him a letter in 1984 or 1985, on which was written: "Copyleft – <a href="/wiki/All_rights_reversed" title="All rights reversed">all rights reversed</a>", which is a pun on the common copyright disclaimer "<a href="/wiki/All_rights_reserved" title="All rights reserved">all rights reserved</a>".<sup id="cite_ref-autogenerated1_11-1" class="reference"><a href="#cite_note-autogenerated1-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p><p>In <a href="/wiki/France" title="France">France</a>, a series of meetings taking place in 2000 under the title "Copyleft Attitude" gave birth to the <a href="/wiki/Free_Art_License" title="Free Art License">Free Art License</a> (FAL),<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> theoretically valid in any jurisdiction bound by the <a href="/wiki/Berne_Convention" title="Berne Convention">Berne Convention</a> and recommended by Stallman's own <a href="/wiki/Free_Software_Foundation" title="Free Software Foundation">Free Software Foundation</a>.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> Shortly thereafter, a separate, unrelated initiative in the <a href="/wiki/United_States" title="United States">United States</a> yielded the <a href="/wiki/Creative_Commons_license" title="Creative Commons license">Creative Commons license</a>, available since 2001 in several different versions (only some of which can be described as copyleft)<sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Please_clarify" title="Wikipedia:Please clarify"><span title="The text near this tag needs further explanation. (July 2024)">further explanation needed</span></a></i>]</sup> and more specifically tailored to U.S. law. </p> <div class="mw-heading mw-heading2"><h2 id="Copyleft_principles">Copyleft principles</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=2" title="Edit section: Copyleft principles"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Freedom">Freedom</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=3" title="Edit section: Freedom"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>While copyright law gives software authors control over copying, distribution and modification of their works, the goal of copyleft is to give all users of the work the freedom to carry out all of these activities. These freedoms (from the <a href="/wiki/Free_Software_Definition" class="mw-redirect" title="Free Software Definition">Free Software Definition</a>) include:<sup id="cite_ref-Carver_2005_7-1" class="reference"><a href="#cite_note-Carver_2005-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p> <dl><dt>Freedom 0</dt> <dd>the freedom to use the work</dd> <dt>Freedom 1</dt> <dd>the freedom to study the work</dd> <dt>Freedom 2</dt> <dd>the freedom to copy and share the work with others</dd> <dt>Freedom 3</dt> <dd>the freedom to modify the work, and the freedom to distribute modified and therefore derivative works</dd></dl> <p>Similar terms are present in the <a href="/wiki/Open_Source_definition" class="mw-redirect" title="Open Source definition">Open Source Definition</a>, a separate definition that contains similar freedoms. The vast majority of copyleft licenses satisfy both definitions, that of the Free Software Definition and Open Source Definition.<sup id="cite_ref-Carver_2005_7-2" class="reference"><a href="#cite_note-Carver_2005-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> By guaranteeing viewers and users of a work the freedom and permission to reproduce, <a href="/wiki/Derivative_work" title="Derivative work">adapt</a>, or distribute it, copyleft licenses are distinct from other types of copyright licenses that limit such freedoms. </p> <div class="mw-heading mw-heading3"><h3 id="Reciprocity">Reciprocity</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=4" title="Edit section: Reciprocity"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Instead of allowing a work to fall completely into the <a href="/wiki/Public_domain" title="Public domain">public domain</a>, where no ownership of copyright is claimed, copyleft allows authors to impose restrictions on the use of their work. One of the main restrictions imposed by copyleft is that <a href="/wiki/Derivative_work" title="Derivative work">derived works</a> must also be released under a compatible copyleft license.<sup id="cite_ref-Carver_2005_7-3" class="reference"><a href="#cite_note-Carver_2005-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p>This is due to the underlying principle of copyleft: that anyone can benefit freely from the previous work of others, but that any modifications to that work should benefit everyone else as well, and thus must be released under similar terms. For this reason, copyleft licenses are also known as <a href="/wiki/Reciprocity_(social_psychology)" title="Reciprocity (social psychology)">reciprocal</a> licenses: any modifiers of a copyleft-licensed work are expected to reciprocate the author's action of copyleft-licensing the software by also copyleft-licensing any derivatives they might have made. Because of this requirement, copyleft licenses have also been described as "viral" due to their self-perpetuating terms.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> </p><p>In addition to restrictions on copying, copyleft licenses address other possible impediments. They ensure that rights cannot be later <a href="/wiki/Revoke" title="Revoke">revoked</a>, and require the work and its derivatives to be provided in a form that allows further modifications to be made. In <a href="/wiki/Computer_software" class="mw-redirect" title="Computer software">software</a>, this means requiring that the <a href="/wiki/Source_code" title="Source code">source code</a> of the derived work be made available together with the software itself.<sup id="cite_ref-Carver_2005_7-4" class="reference"><a href="#cite_note-Carver_2005-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Economic_incentive">Economic incentive</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=5" title="Edit section: Economic incentive"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The economic incentives to work on copyleft content can vary. Traditional copyright law is designed to promote progress by providing economic benefits to creators. When choosing to copyleft their work, content creators may seek complementary benefits like recognition from their peers. </p><p>In the world of computer programming, copyleft-licensed computer programs are often created by programmers to fill a need they have noticed. Such programs are often published with a copyleft license simply to ensure that subsequent users can also freely use modified versions of that program. This is especially true for creators who wish to prevent "open source hijacking", or the act of reusing open-source code and then adding extra restrictions to it, an action prevented by copyleft-licensing the software. Some creators, such as <a href="/wiki/Elastic_NV" title="Elastic NV">Elastic</a>,<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> feel that preventing <a href="/wiki/Corporation" title="Corporation">commercial</a> enterprises from using and then selling their product under a proprietary license is also an incentive. </p><p>Furthermore, the <a href="/wiki/Open_source" title="Open source">open-source</a> culture of programming has been described as a <a href="/wiki/Gift_economy" title="Gift economy">gift economy</a>, where social power is determined by an individual's contributions.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> Contributing to or creating open-source, copyleft-licensed software of high quality can lead to contributors gaining valuable experience and can lead to future career opportunities.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> </p><p>Copyleft software has economic effects beyond individual creators. The presence of quality copyleft software can force proprietary software developers to increase the quality of their software to compete with free software.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> This may also have the effect of preventing monopolies in areas dominated by proprietary software. However, competition with proprietary software can also be a reason to forgo copyleft. The <a href="/wiki/Free_Software_Foundation" title="Free Software Foundation">Free Software Foundation</a> recommends that when "widespread use of the code is vital for advancing the cause of free software",<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> allowing the code to be copied and used freely is more important than a copyleft. </p> <div class="mw-heading mw-heading2"><h2 id="Copyleft_application">Copyleft application</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=6" title="Edit section: Copyleft application"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Common practice for using copyleft is to codify the copying terms for a work with a <a href="/wiki/License" title="License">license</a>. Any such license typically includes all the provisions and principles of copyleft inside the license's terms. This includes the freedom to use the work, study the work, copy, and share the work with others, modify the work, and distribute exact or modified versions of that work, with or without a fee.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> </p><p>Unlike similar permissive licenses that also grant these freedoms, copyleft licenses also ensure that any modified versions of a work covered by a copyleft license must also grant these freedoms. Thus, copyleft licenses have conditions: that modifications of any work licensed under a copyleft license must be distributed under a compatible copyleft scheme and that the distributed modified work must include a means of modifying the work. Under <a href="/wiki/Fair_use" title="Fair use">fair use</a>, however, copyleft licenses may be superseded, just like regular copyrights. Therefore, any person utilizing a source licensed under a copyleft license for works they invent is free to choose any other license (or none at all) provided they meet the fair use standard.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> </p><p>Copyleft licenses necessarily make creative use of relevant rules and laws to enforce their provisions. For example, when using copyright law, those who contribute to a work under copyleft usually must gain, defer, or assign copyright holder status.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (June 2022)">citation needed</span></a></i>]</sup> By submitting the copyright of their contributions under a copyleft license, they deliberately give up some of the rights that normally follow from copyright, including the right to be the unique distributor of copies of the work. </p><p>Some laws used for copyleft licenses vary from one country to another, and may also be granted in terms that vary from country to country. For example, in some countries, it is acceptable to sell a software product without warranty, in standard <a href="/wiki/GNU_General_Public_License" title="GNU General Public License">GNU General Public License</a> style, while in most <a href="/wiki/European_countries" class="mw-redirect" title="European countries">European countries</a> it is not permitted for a software distributor to <a href="/wiki/Waiver" title="Waiver">waive</a> all warranties regarding a sold product.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (June 2022)">citation needed</span></a></i>]</sup> For this reason, the extent of such warranties is specified in most European copyleft licenses, for example, the <a href="/wiki/European_Union_Public_Licence" title="European Union Public Licence">European Union Public Licence</a> (EUPL),<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> or the <a href="/wiki/CeCILL_license" class="mw-redirect" title="CeCILL license">CeCILL license</a>,<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> a license that allows one to use GNU GPL in combination with a limited warranty. </p><p>For projects which will be run over a network, a variation of the GNU GPL, called the <a href="/wiki/Affero_General_Public_License" class="mw-redirect" title="Affero General Public License">Affero General Public License</a> (GNU AGPL), ensures that the source code is available to users of software over a network. </p> <div class="mw-heading mw-heading2"><h2 id="Types_and_relation_to_other_licenses">Types and relation to other licenses</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=7" title="Edit section: Types and relation to other licenses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Free-software_licence#Restrictions" class="mw-redirect" title="Free-software licence">Free-software licence § Restrictions</a></div> <table class="wikitable"> <tbody><tr> <th rowspan="2"> </th> <th colspan="3"><a href="/wiki/Free_software" title="Free software">Free</a> </th> <th colspan="3"><a href="/wiki/Proprietary_software" title="Proprietary software">Non-free</a> </th></tr> <tr> <th><a href="/wiki/Public_domain" title="Public domain">Public domain</a> & <a href="/wiki/Public-domain-equivalent_license" title="Public-domain-equivalent license">equivalents</a> </th> <th width=""><span class="nowrap"><a href="/wiki/Permissive_license" class="mw-redirect" title="Permissive license">Permissive license</a></span></th> <th style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Copyleft (protective license)</th> <th width=""><span class="nowrap"><a href="/wiki/Non-commercial_activity" title="Non-commercial activity">Noncommercial</a> license</span></th> <th><a href="/wiki/Proprietary_license" class="mw-redirect" title="Proprietary license">Proprietary license</a></th> <th><a href="/wiki/Trade_secret" title="Trade secret">Trade secret</a> </th></tr> <tr> <th scope="row">Description </th> <td>Grants all rights</td> <td>Grants use rights, including right to relicense (allows proprietization, <a href="/wiki/License_compatibility" title="License compatibility">license compatibility</a>)</td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Grants use rights, forbids <a href="/wiki/Proprietization" class="mw-redirect" title="Proprietization">proprietization</a></td> <td>Grants rights for noncommercial use only. May be combined with share-alike.</td> <td>Traditional use of <a href="/wiki/Copyright" title="Copyright">copyright</a>; certain rights may or may not be granted</td> <td>No information made public </td></tr> <tr> <th scope="row">For software </th> <td>PD, <a href="/wiki/Unlicense" title="Unlicense">Unlicense</a>, <a href="/wiki/CC0" class="mw-redirect" title="CC0">CC0</a></td> <td><a href="/wiki/BSD_licenses" title="BSD licenses">BSD</a>, <a href="/wiki/MIT_License" title="MIT License">MIT</a>, <a href="/wiki/Apache_License" title="Apache License">Apache</a></td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes"><a href="/wiki/GPL" class="mw-redirect" title="GPL">GPL</a>, <a href="/wiki/GNU_Affero_General_Public_License" title="GNU Affero General Public License">AGPL</a></td> <td><a href="/wiki/Java_Research_License" title="Java Research License">JRL</a>, <a href="/wiki/Aladdin_Free_Public_License" title="Aladdin Free Public License">AFPL</a></td> <td><a href="/wiki/Proprietary_software" title="Proprietary software">Proprietary software</a>, no public license</td> <td>Private, internal software </td></tr> <tr> <th scope="row">For other creative works </th> <td>PD, <a href="/wiki/CC0" class="mw-redirect" title="CC0">CC0</a></td> <td><a href="/wiki/CC_BY" class="mw-redirect" title="CC BY">CC BY</a></td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes"><a href="/wiki/CC_BY-SA" class="mw-redirect" title="CC BY-SA">CC BY-SA</a>, <a href="/wiki/Free_Art_License" title="Free Art License">FAL</a></td> <td><a href="/wiki/CC_BY-NC" class="mw-redirect" title="CC BY-NC">CC BY-NC</a></td> <td><a href="/wiki/Copyright" title="Copyright">Copyright</a>, no public license, <a href="/wiki/Creative_Commons_license" title="Creative Commons license">CC BY-ND</a></td> <td>Unpublished </td></tr></tbody></table> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Cc-sa.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/29/Cc-sa.svg/150px-Cc-sa.svg.png" decoding="async" width="150" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/29/Cc-sa.svg/225px-Cc-sa.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/29/Cc-sa.svg/300px-Cc-sa.svg.png 2x" data-file-width="64" data-file-height="64" /></a><figcaption>The <a href="/wiki/Creative_Commons" title="Creative Commons">Creative Commons</a> icon for Share-Alike, a variant of the copyleft symbol</figcaption></figure> <p>Copyleft is a distinguishing feature of some <a href="/wiki/Free_software" title="Free software">free software</a> licenses, while other <a href="/wiki/Free_software_license" class="mw-redirect" title="Free software license">free-software licenses</a> are not copyleft licenses because they do not require the licensee to distribute derivative works under the same license. There is an ongoing debate as to which class of license provides the greater degree of freedom. This debate hinges on complex issues, such as the definition of freedom and whose freedoms are more important: the potential future recipients of a work (freedom from proprietization) or just the initial recipient (freedom to proprietize). However, current copyright law and the availability of both types of licenses, copyleft and permissive, allow authors to choose the type under which to license the works they invent. </p><p>For documents, art, and other works other than software and code, the <a href="/wiki/Share-alike" title="Share-alike">Creative Commons share-alike licensing system</a> and the <a href="/wiki/GNU_Free_Documentation_License" title="GNU Free Documentation License">GNU Free Documentation License</a> (GFDL) allow authors to apply limitations to certain sections of their work, exempting some parts of the work from the full copyleft mechanism. In the case of the GFDL, these limitations include the use of invariant sections, which may not be altered by future editors. The initial intention of the GFDL was as a device for supporting the <a href="/wiki/Documentation" title="Documentation">documentation</a> of copylefted software. However, the result is that it can be used for any kind of document. </p> <div class="mw-heading mw-heading3"><h3 id="Strong_and_weak_copyleft">Strong and weak copyleft</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=8" title="Edit section: Strong and weak copyleft"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The strength of the copyleft license governing a work is determined by the extent to which its provisions can be imposed on all kinds of derivative works. Thus, the term "weak copyleft" refers to licenses where not all derivative works inherit the copyleft license; whether a derivative work inherits or not often depends on how it was derived. </p><p>"Weak copyleft" licenses are often used to cover <a href="/wiki/Library_(computing)" title="Library (computing)">software libraries</a>. This allows other software to link to the library and be redistributed without the requirement for the linking software to also be licensed under the same terms. Only changes to the software licensed under a "weak copyleft" license become subject itself to copyleft provisions of such a license. This allows programs of any license to be compiled and linked against copylefted libraries such as <a href="/wiki/GNU_C_Library" class="mw-redirect" title="GNU C Library">glibc</a> and then redistributed without any re-licensing required. The concrete effect of strong vs. weak copyleft has yet to be tested in court.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> Free-software licenses that use "weak" copyleft include the <a href="/wiki/GNU_Lesser_General_Public_License" title="GNU Lesser General Public License">GNU Lesser General Public License</a> and the <a href="/wiki/Mozilla_Public_License" title="Mozilla Public License">Mozilla Public License</a>. </p><p>The <a href="/wiki/GNU_General_Public_License" title="GNU General Public License">GNU General Public License</a> is an example of a license implementing strong copyleft. An even stronger copyleft license is the <a href="/wiki/GNU_Affero_General_Public_License" title="GNU Affero General Public License">AGPL</a>, which requires the publishing of the source code for <a href="/wiki/Software_as_a_service" title="Software as a service">software as a service</a> use cases.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-fsf2_30-0" class="reference"><a href="#cite_note-fsf2-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p><p>The <a href="/wiki/Sybase_Open_Watcom_Public_License" title="Sybase Open Watcom Public License">Sybase Open Watcom Public License</a> is one of the strongest copyleft licenses, as this license closes the so-called "private usage" loophole of the GPL, and requires the publishing of source code in any use case. For this reason, the license is considered non-free by the <a href="/wiki/Free_Software_Foundation" title="Free Software Foundation">Free Software Foundation</a>, the <a href="/wiki/GNU_Project" title="GNU Project">GNU Project</a>, and the <a href="/wiki/Debian" title="Debian">Debian</a> project.<sup id="cite_ref-fsf-watcom_31-0" class="reference"><a href="#cite_note-fsf-watcom-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> However, the license is accepted as <a href="/wiki/Open_source" title="Open source">open source</a> by the <a href="/wiki/Open_Source_Initiative" title="Open Source Initiative">OSI</a>. </p><p>The <a href="/wiki/Design_Science_License" title="Design Science License">Design Science License</a> (DSL) is a strong copyleft license that applies to any work, not only software or documentation, but also literature, artworks, music, photography, and video. DSL was written by Michael Stutz after he took an interest in applying GNU-style copyleft to non-software works, which later came to be called <a href="/wiki/Libre_content" class="mw-redirect" title="Libre content">libre works</a>. In the 1990s, it was used on music recordings, visual art, and even novels. It is not considered compatible with the GNU GPL by the Free Software Foundation.<sup id="cite_ref-fsf_32-0" class="reference"><a href="#cite_note-fsf-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Full_and_partial_copyleft">Full and partial copyleft</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=9" title="Edit section: Full and partial copyleft"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>"Full" and "partial" copyleft relate to another issue. Full copyleft exists when all parts of a work (except the license itself) may only be modified and distributed under the terms of the work's copyleft license. Partial copyleft, by contrast, exempts some parts of the work from the copyleft provisions, permitting distribution of some modifications under terms other than the copyleft license, or in some other way does not impose all the principles of copylefting on the work. An example of partial copyleft is the GPL linking exception made for some software packages. </p> <div class="mw-heading mw-heading3"><h3 id="Share-alike">Share-alike</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=10" title="Edit section: Share-alike"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The "<a href="/wiki/Share-alike" title="Share-alike">share-alike</a>" condition in some licenses imposes the requirement that any freedom that is granted regarding the original work must be granted on exactly the same or compatible terms in any derived work. </p><p>This implies that any copyleft license is automatically a share-alike license but not the other way around, as some share-alike licenses include further restrictions such as prohibiting commercial use. Another restriction is that not everyone wants to share their work, and some share-alike agreements require that the whole body of work be shared, even if the author only wants to share a certain part. The plus side for an author of source code is that any modification to the code will not only benefit the original author but that the author will be recognized and ensure the same or compatible license terms cover the changed code.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> Some Creative Commons licenses are examples of share-alike copyleft licenses. </p> <div class="mw-heading mw-heading3"><h3 id="Permissive_licenses">Permissive licenses</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=11" title="Edit section: Permissive licenses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Permissive_software_license" title="Permissive software license">Permissive software license</a></div> <p>Those licenses grant users of the software the same freedoms as copyleft licenses but do not require modified versions of that software to also include those freedoms. They have minimal restrictions on how the software can be used, modified, and redistributed, and are thus not copyleft licenses. Examples of this type of license include the <a href="/wiki/X11_license" class="mw-redirect" title="X11 license">X11 license</a>, <a href="/wiki/Apache_License" title="Apache License">Apache license</a>, <a href="/wiki/MIT_license" class="mw-redirect" title="MIT license">Expat license</a>, and the various <a href="/wiki/BSD_licenses" title="BSD licenses">BSD licenses</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Debate_and_controversy">Debate and controversy</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=12" title="Edit section: Debate and controversy"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>It has been suggested that copyleft has become a divisive issue in the ideological strife between the <a href="/wiki/Open_Source_Initiative" title="Open Source Initiative">Open Source Initiative</a> and the <a href="/wiki/Free_software_movement" title="Free software movement">free software movement</a>.<sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> However, there is evidence that copyleft is both accepted and proposed by both parties: </p> <ul><li>Both the OSI and the FSF have copyleft and non-copyleft licenses in their respective lists of accepted licenses.<sup id="cite_ref-osi_35-0" class="reference"><a href="#cite_note-osi-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-fsf_32-1" class="reference"><a href="#cite_note-fsf-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup></li> <li>The OSI's original Legal Counsel <a href="/wiki/Lawrence_Rosen_(attorney)" title="Lawrence Rosen (attorney)">Lawrence Rosen</a> has written a copyleft license, the <a href="/wiki/Open_Software_License" title="Open Software License">Open Software License</a>.</li> <li>The OSI's licensing how-to recognises the GPL as a "best practice" license.<sup id="cite_ref-36" class="reference"><a href="#cite_note-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup></li> <li>Some of the software programs of the GNU Project are published under non-copyleft licenses.<sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup></li> <li>Stallman has endorsed the use of non-copyleft licenses in certain circumstances, for example in the case of the <a href="/wiki/Ogg_Vorbis" class="mw-redirect" title="Ogg Vorbis">Ogg Vorbis</a> <a href="/wiki/Relicensing" class="mw-redirect" title="Relicensing">relicensing</a>.<sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading3"><h3 id=""Viral"_licensing"><span id=".22Viral.22_licensing"></span>"Viral" licensing</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=13" title="Edit section: "Viral" licensing"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/GNU_General_Public_License#"Viral"_nature" title="GNU General Public License">GNU General Public License § "Viral" nature</a></div> <p>"<b>Viral license</b>" is a pejorative name for copyleft licenses.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-42" class="reference"><a href="#cite_note-42"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-43" class="reference"><a href="#cite_note-43"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup> It originates from the terms 'General Public Virus' or 'GNU Public Virus' (GPV), which dates back to 1990, a year after the GPLv1 was released.<sup id="cite_ref-44" class="reference"><a href="#cite_note-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-45" class="reference"><a href="#cite_note-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup> The name 'viral license' refers to the fact that any works derived from a copyleft work must preserve the copyleft permissions when distributed. </p><p>Some advocates of the various <a href="/wiki/BSD_Licenses" class="mw-redirect" title="BSD Licenses">BSD Licenses</a> used the term derisively in regards to the GPL's tendency to absorb BSD-licensed code without allowing the original BSD work to benefit from it, while at the same time promoting itself as "freer" than other licenses.<sup id="cite_ref-47" class="reference"><a href="#cite_note-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-48" class="reference"><a href="#cite_note-48"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-49" class="reference"><a href="#cite_note-49"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Microsoft" title="Microsoft">Microsoft</a> vice-president <a href="/wiki/Craig_Mundie" title="Craig Mundie">Craig Mundie</a> remarked, "This viral aspect of the GPL poses a threat to the intellectual property of any organization making use of it."<sup id="cite_ref-50" class="reference"><a href="#cite_note-50"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> In another context, <a href="/wiki/Steve_Ballmer" title="Steve Ballmer">Steve Ballmer</a> declared that code released under GPL is useless to the commercial sector, since it can only be used if the resulting surrounding code is licensed under a GPL-compatible license, and described it thus as "a cancer that attaches itself in an intellectual property sense to everything it touches".<sup id="cite_ref-51" class="reference"><a href="#cite_note-51"><span class="cite-bracket">[</span>51<span class="cite-bracket">]</span></a></sup> </p><p>In response to Microsoft's attacks on the GPL, several prominent free-software developers and advocates released a joint statement supporting the license.<sup id="cite_ref-52" class="reference"><a href="#cite_note-52"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> According to <a href="/wiki/Free_Software_Foundation" title="Free Software Foundation">FSF</a> compliance engineer David Turner, the term "viral license" creates a misunderstanding and a fear of using copylefted free software.<sup id="cite_ref-53" class="reference"><a href="#cite_note-53"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup> While a person can catch a virus without active action, license conditions take effect upon effective usage or adoption.<sup id="cite_ref-54" class="reference"><a href="#cite_note-54"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup> David McGowan has also written that there is no reason to believe the GPL could force proprietary software to become free software, but could "try to enjoin the firm from distributing commercially a program that combined with the GPL'd code to form a derivative work, and to recover damages for infringement." If the firm "actually copied code from a GPL'd program, such a suit would be a perfectly ordinary assertion of copyright, which most private firms would defend if the shoe were on the other foot."<sup id="cite_ref-55" class="reference"><a href="#cite_note-55"><span class="cite-bracket">[</span>55<span class="cite-bracket">]</span></a></sup> Richard Stallman has described this view with an analogy, saying, "The GPL's domain does not spread by proximity or contact, only by deliberate inclusion of GPL-covered code in your program. It spreads like a <a href="/wiki/Chlorophytum_comosum" title="Chlorophytum comosum">spider plant</a>, not like a virus."<sup id="cite_ref-56" class="reference"><a href="#cite_note-56"><span class="cite-bracket">[</span>56<span class="cite-bracket">]</span></a></sup> </p><p>Popular copyleft licenses, such as the GPL, have a clause allowing components to interact with non-copyleft components as long as the communication is abstract,<sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability"><span title="source does not use word abstract once and it also does not lay out clear guidelines, just gives some rather vague examples (May 2020)">failed verification</span></a></i>]</sup> such as executing a command-line tool with a set of switches or interacting with a web server.<sup id="cite_ref-57" class="reference"><a href="#cite_note-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> As a consequence, even if one module of an otherwise non-copyleft product is placed under the GPL, it may still be legal for other components to communicate with it in ways such as these.<sup class="noprint Inline-Template" style="margin-left:0.1em; white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Please_clarify" title="Wikipedia:Please clarify"><span title="it may also not be legal, this is written to favour one point of view (May 2020)">clarification needed</span></a></i>]</sup> This allowed communication may or may not include reusing libraries or routines via <a href="/wiki/Library_(computing)" title="Library (computing)">dynamic linking</a> – some commentators say it does,<sup id="cite_ref-58" class="reference"><a href="#cite_note-58"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> the FSF asserts it does not and explicitly adds an <a href="/wiki/GPL_linking_exception" title="GPL linking exception">exception allowing it</a> in the license for the <a href="/wiki/GNU_Classpath" title="GNU Classpath">GNU Classpath</a> re-implementation of the Java library. This ambiguity is an important difference between the GPL and the <a href="/wiki/LGPL" class="mw-redirect" title="LGPL">LGPL</a>, in that the LGPL specifically allows linking or compiling works licensed under terms that are not compatible with the LGPL, with works covered by the LGPL.<sup id="cite_ref-not_use_LGPL_59-0" class="reference"><a href="#cite_note-not_use_LGPL-59"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Symbol">Symbol</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=14" title="Edit section: Symbol"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1092331828">@media(min-width:720px){.mw-parser-output .contains-special-characters{width:22em}}</style><div class="side-box metadata side-box-right contains-special-characters noprint selfref"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1126788409"> <div class="side-box-flex"> <div class="side-box-image"><span class="skin-invert" typeof="mw:File"><a href="/wiki/Specials_(Unicode_block)#Replacement_character" title="Specials (Unicode block)"><img alt="<?>" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Replacement_character.svg/40px-Replacement_character.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Replacement_character.svg/60px-Replacement_character.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Replacement_character.svg/80px-Replacement_character.svg.png 2x" data-file-width="200" data-file-height="200" /></a></span></div> <div class="side-box-text plainlist">You may need <a href="/wiki/Help:Multilingual_support" title="Help:Multilingual support">rendering support</a> to display the uncommon <a href="/wiki/Unicode" title="Unicode">Unicode</a> characters in this section correctly.</div></div> </div> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox" style="max-width:20em;"><tbody><tr><th colspan="2" class="infobox-above" style="background: #ccc; font-size: 500%; line-height:1.3; font-weight:normal; font-family:'times new roman', times, georgia, serif, sans-serif;"><span style="display:inline-block; transform: scaleX(-1);" title="Reversed U+00A9">©</span> <span title="U+1F12F">🄯</span></th></tr><tr><th colspan="2" class="infobox-header" style="background: #ccc;"><div style="background: #ccc; font-size: 125%; font-weight: bold; padding: 0.1em 0.25em 0.2em; line-height: 1.2em;">Copyleft symbol</div></th></tr><tr><th scope="row" class="infobox-label">In <a href="/wiki/Unicode" title="Unicode">Unicode</a></th><td class="infobox-data"><span class="nowrap"><style data-mw-deduplicate="TemplateStyles:r886049734">.mw-parser-output .monospaced{font-family:monospace,monospace}</style><span class="monospaced">U+1F12F</span> </span><span style="font-size:125%;line-height:1em">🄯</span> <span style="font-variant: small-caps; text-transform: lowercase;">COPYLEFT SYMBOL</span><br /><span class="nowrap">Alternative symbol: (ɔ)</span></td></tr><tr><th colspan="2" class="infobox-header" style="background: #ccc;">Different from</th></tr><tr><th scope="row" class="infobox-label">Different from</th><td class="infobox-data"><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+00A9</span> </span><span style="font-size:125%;line-height:1em">©</span> <span style="font-variant: small-caps; text-transform: lowercase;"><a href="/wiki/Copyright_symbol" title="Copyright symbol">COPYRIGHT SIGN</a></span></td></tr></tbody></table> <p>The copyleft symbol is a mirrored version of the <a href="/wiki/Copyright_symbol" title="Copyright symbol">copyright symbol</a>, <span class="nounderlines" style="border: 1px solid var(--border-color-muted,#ddd); color: var(--color-base); background-color: var( --background-color-neutral-subtle, #fdfdfd); padding: 1px 1px;">©</span>: a reversed C in a circle.<sup id="cite_ref-60" class="reference"><a href="#cite_note-60"><span class="cite-bracket">[</span>60<span class="cite-bracket">]</span></a></sup> A 2016 proposal to add the symbol to a future version of Unicode was accepted by the <a href="/wiki/Unicode_Technical_Committee" class="mw-redirect" title="Unicode Technical Committee">Unicode Technical Committee</a>.<sup id="cite_ref-61" class="reference"><a href="#cite_note-61"><span class="cite-bracket">[</span>61<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-UnicodePipeline_62-0" class="reference"><a href="#cite_note-UnicodePipeline-62"><span class="cite-bracket">[</span>62<span class="cite-bracket">]</span></a></sup> The code point <span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1F12F</span> </span><span style="font-size:125%;line-height:1em">🄯</span> <span style="font-variant: small-caps; text-transform: lowercase;">COPYLEFT SYMBOL</span> was added in <a href="/wiki/Unicode_11" class="mw-redirect" title="Unicode 11">Unicode 11</a>.<sup id="cite_ref-UnicodePipeline_62-1" class="reference"><a href="#cite_note-UnicodePipeline-62"><span class="cite-bracket">[</span>62<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-63" class="reference"><a href="#cite_note-63"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup> The copyleft symbol has no legal status.<sup id="cite_ref-64" class="reference"><a href="#cite_note-64"><span class="cite-bracket">[</span>64<span class="cite-bracket">]</span></a></sup> </p><p>As of 2024,<sup class="plainlinks noexcerpt noprint asof-tag update" style="display:none;"><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Copyleft&action=edit">[update]</a></sup> the symbol is generally provided as standard in the <a href="/wiki/System_font" class="mw-redirect" title="System font">system fonts</a> of most current <a href="/wiki/Operating_systems" class="mw-redirect" title="Operating systems">operating systems</a>,<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (May 2024)">citation needed</span></a></i>]</sup> but if need be it may be approximated with character <span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+2184</span> </span><span style="font-size:125%;line-height:1em">ↄ</span> <span style="font-variant: small-caps; text-transform: lowercase;">LATIN SMALL LETTER REVERSED C</span> between parenthesis <span class="nounderlines" style="border: 1px solid var(--border-color-muted,#ddd); color: var(--color-base); background-color: var( --background-color-neutral-subtle, #fdfdfd); padding: 1px 1px;">(ɔ)</span>. </p> <div class="mw-heading mw-heading3"><h3 id="Typing_the_character">Typing the character</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=15" title="Edit section: Typing the character"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>On modern computer systems, the character <span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1F12F</span> </span><span style="font-size:125%;line-height:1em">🄯</span> <span style="font-variant: small-caps; text-transform: lowercase;">COPYLEFT SYMBOL</span> can be generated using one of these methods (<a href="/wiki/Keyboard_shortcut" title="Keyboard shortcut">keyboard shortcuts</a>): </p> <ul><li><a href="/wiki/ChromeOS" title="ChromeOS">ChromeOS</a>: <style data-mw-deduplicate="TemplateStyles:r1249182868">.mw-parser-output .keyboard-key{border:1px solid #aaa;border-radius:0.2em;box-shadow:0.1em 0.1em 0.2em rgba(0,0,0,0.1);background-color:var(--background-color-neutral-subtle,#f8f9fa);background-image:linear-gradient(to bottom,var(--background-color-neutral,#eaecf0),var(--background-color-neutral-subtle,#f8f9fa),var(--background-color-neutral,#eaecf0));color:var(--color-base,#202122);padding:0.1em 0.3em;font-family:inherit;font-size:0.85em}</style><kbd class="keyboard-key nowrap">Ctrl</kbd>+<kbd class="keyboard-key nowrap">⇧ Shift</kbd>+<kbd class="keyboard-key nowrap">u</kbd>, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868"><kbd class="keyboard-key nowrap">1F12F</kbd>, then <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868"><kbd class="keyboard-key nowrap">↵ Enter</kbd> or <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868"><kbd class="keyboard-key nowrap">Space</kbd>.<sup id="cite_ref-65" class="reference"><a href="#cite_note-65"><span class="cite-bracket">[</span>65<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/HTML" title="HTML">HTML</a>: <code class="mw-highlight mw-highlight-lang-text mw-content-ltr" style="" dir="ltr">&#127279 or &#x1F12F</code></li> <li><a href="/wiki/Linux" title="Linux">Linux</a>: <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868"><kbd class="keyboard-key nowrap">Ctrl</kbd>+<kbd class="keyboard-key nowrap">⇧ Shift</kbd>+<kbd class="keyboard-key nowrap">u</kbd>, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868"><kbd class="keyboard-key nowrap">1F12F</kbd>, then <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868"><kbd class="keyboard-key nowrap">↵ Enter</kbd> or <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868"><kbd class="keyboard-key nowrap">Space</kbd></li> <li><a href="/wiki/Apple_Mac" class="mw-redirect" title="Apple Mac">Mac</a>: Code point: U+1F12F</li> <li><a href="/wiki/Microsoft_Windows" title="Microsoft Windows">Windows</a>: <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868"><kbd class="keyboard-key nowrap"><a href="/wiki/Alt_code" title="Alt code">Alt</a></kbd>+<kbd class="keyboard-key nowrap">1F12F</kbd></li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=16" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239009302">.mw-parser-output .portalbox{padding:0;margin:0.5em 0;display:table;box-sizing:border-box;max-width:175px;list-style:none}.mw-parser-output .portalborder{border:1px solid var(--border-color-base,#a2a9b1);padding:0.1em;background:var(--background-color-neutral-subtle,#f8f9fa)}.mw-parser-output .portalbox-entry{display:table-row;font-size:85%;line-height:110%;height:1.9em;font-style:italic;font-weight:bold}.mw-parser-output .portalbox-image{display:table-cell;padding:0.2em;vertical-align:middle;text-align:center}.mw-parser-output .portalbox-link{display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle}@media(min-width:720px){.mw-parser-output .portalleft{clear:left;float:left;margin:0.5em 1em 0.5em 0}.mw-parser-output .portalright{clear:right;float:right;margin:0.5em 0 0.5em 1em}}</style><ul role="navigation" aria-label="Portals" class="noprint portalbox portalborder portalright"> <li class="portalbox-entry"><span class="portalbox-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/31/Free_and_open-source_software_logo_%282009%29.svg/28px-Free_and_open-source_software_logo_%282009%29.svg.png" decoding="async" width="28" height="28" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/31/Free_and_open-source_software_logo_%282009%29.svg/42px-Free_and_open-source_software_logo_%282009%29.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/31/Free_and_open-source_software_logo_%282009%29.svg/56px-Free_and_open-source_software_logo_%282009%29.svg.png 2x" data-file-width="512" data-file-height="512" /></span></span></span><span class="portalbox-link"><a href="/wiki/Portal:Free_and_open-source_software" title="Portal:Free and open-source software">Free and open-source software portal</a></span></li></ul> <style data-mw-deduplicate="TemplateStyles:r1184024115">.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output .div-col ul{margin-top:0}.mw-parser-output .div-col li,.mw-parser-output .div-col dd{page-break-inside:avoid;break-inside:avoid-column}</style><div class="div-col"> <ul><li><a href="/wiki/Category:Copyleft_software_licenses" title="Category:Copyleft software licenses">List of copyleft software licenses</a></li> <li><a href="/wiki/All_rights_reversed" title="All rights reversed">All rights reversed</a></li> <li><a href="/wiki/Anti-copyright_notice" title="Anti-copyright notice">Anti-copyright notice</a></li> <li><a href="/wiki/Commercial_use_of_copyleft_works" title="Commercial use of copyleft works">Commercial use of copyleft works</a></li> <li><a href="/wiki/Comparison_of_open_source_and_closed_source" class="mw-redirect" title="Comparison of open source and closed source">Comparison of open source and closed source</a></li> <li><a href="/wiki/Copyfraud" title="Copyfraud">Copyfraud</a></li> <li><a href="/wiki/Copyright_abolition" title="Copyright abolition">Copyright abolition</a></li> <li><a href="/wiki/Copyright_alternatives" title="Copyright alternatives">Copyright alternatives</a></li> <li><a href="/wiki/Intellectual_property#Criticisms" title="Intellectual property">Criticism of intellectual property</a></li> <li><a href="/wiki/Internet_freedom" title="Internet freedom">Internet freedom</a></li> <li><a href="/wiki/Free_content" title="Free content">Free content</a></li> <li><a href="/wiki/Free_Culture_movement" class="mw-redirect" title="Free Culture movement">Free Culture movement</a></li> <li><a href="/wiki/Free_software_movement" title="Free software movement">Free software movement</a></li> <li><a href="/wiki/History_of_free_and_open-source_software" title="History of free and open-source software">History of free and open-source software</a></li> <li><a href="/wiki/Criticism_of_copyright" title="Criticism of copyright">Criticism of copyright</a></li> <li><a href="/wiki/Public_copyright_license" title="Public copyright license">Public copyright license</a></li> <li><a href="/wiki/Free_video" title="Free video">Free video</a></li> <li><i><a href="/wiki/Steal_This_Film" title="Steal This Film">Steal This Film</a></i></li> <li><a href="/wiki/In_Praise_of_Copying" title="In Praise of Copying">In Praise of Copying</a></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=17" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFNewman2011" class="citation journal cs1">Newman, John (29 December 2011). "Copyright and Open Access at the Bedside". <i>NEJM</i>. <b>365</b> (26): 2447–2449. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1056%2FNEJMp1110652">10.1056/NEJMp1110652</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/22204721">22204721</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=NEJM&rft.atitle=Copyright+and+Open+Access+at+the+Bedside&rft.volume=365&rft.issue=26&rft.pages=2447-2449&rft.date=2011-12-29&rft_id=info%3Adoi%2F10.1056%2FNEJMp1110652&rft_id=info%3Apmid%2F22204721&rft.aulast=Newman&rft.aufirst=John&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-redhat2005-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-redhat2005_2-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFTroan2006" class="citation conference cs1">Troan, Larry (2006). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140122163130/https://www.redhat.com/f/summitfiles/presentation/May31/Open%20Source%20Dynamics/Troan_OpenSourceProprietyPersp.pdf"><i>Open Source from a Proprietary Perspective</i></a> <span class="cs1-format">(PDF)</span>. Red Hat Summit. Nashville: <a href="/wiki/Red_Hat" title="Red Hat">Red Hat</a>. Archived from <a rel="nofollow" class="external text" href="https://www.redhat.com/f/summitfiles/presentation/May31/Open%20Source%20Dynamics/Troan_OpenSourceProprietyPersp.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 22 January 2014.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=conference&rft.btitle=Open+Source+from+a+Proprietary+Perspective&rft.place=Nashville&rft.pub=Red+Hat&rft.date=2006&rft.aulast=Troan&rft.aufirst=Larry&rft_id=https%3A%2F%2Fwww.redhat.com%2Ff%2Fsummitfiles%2Fpresentation%2FMay31%2FOpen%2520Source%2520Dynamics%2FTroan_OpenSourceProprietyPersp.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFStallman2007" class="citation web cs1">Stallman, Richard (29 June 2007). <a rel="nofollow" class="external text" href="https://www.gnu.org/copyleft/gpl.html">"GNU General Public License"</a>. <i>GNU Project</i><span class="reference-accessdate">. Retrieved <span class="nowrap">1 May</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=GNU+Project&rft.atitle=GNU+General+Public+License&rft.date=2007-06-29&rft.aulast=Stallman&rft.aufirst=Richard&rft_id=https%3A%2F%2Fwww.gnu.org%2Fcopyleft%2Fgpl.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://artlibre.org/licence/lal/en/">"Free Art License 1.3"</a>. <i>Copyleft Attitude</i><span class="reference-accessdate">. Retrieved <span class="nowrap">6 October</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Copyleft+Attitude&rft.atitle=Free+Art+License+1.3&rft_id=https%3A%2F%2Fartlibre.org%2Flicence%2Flal%2Fen%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-cc-by-sa-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-cc-by-sa_5-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/">"Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)"</a>. <i>Creative Commons</i><span class="reference-accessdate">. Retrieved <span class="nowrap">14 August</span> 2015</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Creative+Commons&rft.atitle=Attribution-ShareAlike+4.0+International+%28CC+BY-SA+4.0%29&rft_id=https%3A%2F%2Fcreativecommons.org%2Flicenses%2Fby-sa%2F4.0%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWang1976" class="citation journal cs1"><a href="/wiki/Li-Chen_Wang" title="Li-Chen Wang">Wang, Li-Chen</a> (May 1976). "Palo Alto Tiny BASIC". <i><a href="/wiki/Dr._Dobb%27s_Journal" title="Dr. Dobb's Journal">Dr. Dobb's Journal of Computer Calisthenics & Orthodontia, Running Light Without Overbyte</a></i>. <b>1</b> (5): 12–25.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Dr.+Dobb%27s+Journal+of+Computer+Calisthenics+%26+Orthodontia%2C+Running+Light+Without+Overbyte&rft.atitle=Palo+Alto+Tiny+BASIC&rft.volume=1&rft.issue=5&rft.pages=12-25&rft.date=1976-05&rft.aulast=Wang&rft.aufirst=Li-Chen&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span> Source code begins with the following six lines. <pre>TINY BASIC FOR INTEL 8080 VERSION 1.0 BY LI-CHEN WANG 10 JUNE, 1976 @COPYLEFT ALL WRONGS RESERVED</pre> The June date in the May issue is correct. The magazine was behind schedule, the June and July issues were combined to catch up.</span> </li> <li id="cite_note-Carver_2005-7"><span class="mw-cite-backlink">^ <a href="#cite_ref-Carver_2005_7-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Carver_2005_7-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Carver_2005_7-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Carver_2005_7-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Carver_2005_7-4"><sup><i><b>e</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCarver2005" class="citation journal cs1">Carver, Brian W. (5 April 2005). <a rel="nofollow" class="external text" href="https://lawcat.berkeley.edu/record/1119855?ln=en">"Share and Share Alike: Understanding and Enforcing Open Source and Free Software Licenses"</a>. <i>Berkeley Technology Law Journal</i>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.15779%2FZ388T19">10.15779/Z388T19</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:153900462">153900462</a>. <a href="/wiki/SSRN_(identifier)" class="mw-redirect" title="SSRN (identifier)">SSRN</a> <a rel="nofollow" class="external text" href="https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1586574">1586574</a><span class="reference-accessdate">. Retrieved <span class="nowrap">27 June</span> 2023</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Berkeley+Technology+Law+Journal&rft.atitle=Share+and+Share+Alike%3A+Understanding+and+Enforcing+Open+Source+and+Free+Software+Licenses&rft.date=2005-04-05&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A153900462%23id-name%3DS2CID&rft_id=https%3A%2F%2Fpapers.ssrn.com%2Fsol3%2Fpapers.cfm%3Fabstract_id%3D1586574%23id-name%3DSSRN&rft_id=info%3Adoi%2F10.15779%2FZ388T19&rft.aulast=Carver&rft.aufirst=Brian+W.&rft_id=https%3A%2F%2Flawcat.berkeley.edu%2Frecord%2F1119855%3Fln%3Den&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWilliams2002" class="citation book cs1"><a href="/wiki/Sam_Williams_(American_journalist)" class="mw-redirect" title="Sam Williams (American journalist)">Williams, Sam</a> (March 2002). <a rel="nofollow" class="external text" href="http://www.oreilly.com/openbook/freedom/ch07.html">"7"</a>. <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/freeasinfreedomr00will"><i>Free as in Freedom – Richard Stallman's Crusade for Free Software</i></a></span>. <a href="/wiki/O%27Reilly_Media" title="O'Reilly Media">O'Reilly Media</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-596-00287-9" title="Special:BookSources/978-0-596-00287-9"><bdi>978-0-596-00287-9</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=7&rft.btitle=Free+as+in+Freedom+%E2%80%93+Richard+Stallman%27s+Crusade+for+Free+Software&rft.pub=O%27Reilly+Media&rft.date=2002-03&rft.isbn=978-0-596-00287-9&rft.aulast=Williams&rft.aufirst=Sam&rft_id=http%3A%2F%2Fwww.oreilly.com%2Fopenbook%2Ffreedom%2Fch07.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMoody2002" class="citation book cs1"><a href="/wiki/Glyn_Moody" title="Glyn Moody">Moody, Glyn</a> (2002). <i>Rebel Code</i>. p. 26.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Rebel+Code&rft.pages=26&rft.date=2002&rft.aulast=Moody&rft.aufirst=Glyn&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.free-soft.org/gpl_history/emacs_gpl.html">"Emacs General Public License"</a>. 5 July 2001<span class="reference-accessdate">. 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Retrieved <span class="nowrap">24 August</span> 2010</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Free+Software+Licensing+Agreement+CeCILL&rft.pub=INRIA&rft_id=http%3A%2F%2Fwww.inria.fr%2Fvalorisation%2Flogiciels%2FLicence.CeCILL-V1.US.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPatrice-Emmanuel_Schmitz2015" class="citation web cs1">Patrice-Emmanuel Schmitz (3 April 2015). <a rel="nofollow" class="external text" href="https://joinup.ec.europa.eu/community/eupl/news/meaning-%E2%80%9Ccopyleft%E2%80%9D-eupl">"The meaning of "Copyleft" in EUPL"</a>. <i>Joinup</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Joinup&rft.atitle=The+meaning+of+%22Copyleft%22+in+EUPL&rft.date=2015-04-03&rft.au=Patrice-Emmanuel+Schmitz&rft_id=https%3A%2F%2Fjoinup.ec.europa.eu%2Fcommunity%2Feupl%2Fnews%2Fmeaning-%25E2%2580%259Ccopyleft%25E2%2580%259D-eupl&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text">For some of the philosophy behind the term "SaaSS", see the "Server Software" section of <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.gnu.org/licenses/license-recommendations.html">"How to choose a license for your own work"</a>. GNU Project. 20 December 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">1 May</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=How+to+choose+a+license+for+your+own+work&rft.pub=GNU+Project&rft.date=2015-12-20&rft_id=https%3A%2F%2Fwww.gnu.org%2Flicenses%2Flicense-recommendations.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFStallman2016" class="citation web cs1"><a href="/wiki/Richard_Stallman" title="Richard Stallman">Stallman, Richard</a> (18 November 2016). <a rel="nofollow" class="external text" href="https://www.gnu.org/philosophy/who-does-that-server-really-serve.html">"Who does that server really serve?"</a>. <a href="/wiki/GNU_Project" title="GNU Project">GNU Project</a><span class="reference-accessdate">. Retrieved <span class="nowrap">1 May</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Who+does+that+server+really+serve%3F&rft.pub=GNU+Project&rft.date=2016-11-18&rft.aulast=Stallman&rft.aufirst=Richard&rft_id=https%3A%2F%2Fwww.gnu.org%2Fphilosophy%2Fwho-does-that-server-really-serve.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.gnu.org/licenses/why-affero-gpl.html">"Why the Affero GPL"</a>. <a href="/wiki/GNU_Project" title="GNU Project">GNU Project</a>. 10 May 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">1 May</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Why+the+Affero+GPL&rft.pub=GNU+Project&rft.date=2015-05-10&rft_id=https%3A%2F%2Fwww.gnu.org%2Flicenses%2Fwhy-affero-gpl.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-fsf2-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-fsf2_30-0">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.gnu.org/philosophy/license-list.html#AGPL">List of free-software licences on the GNU website</a>: "<i>We recommend that developers consider using the GNU AGPL for any software which will commonly be run over a network</i>".</span> </li> <li id="cite_note-fsf-watcom-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-fsf-watcom_31-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.gnu.org/licenses/license-list.html#Watcom">"Various Licenses and Comments about Them - Sybase Open Watcom Public License version 1.0 (#Watcom)"</a>. GNU<span class="reference-accessdate">. Retrieved <span class="nowrap">23 December</span> 2015</span>. <q>This is not a free software license. It requires you to publish the source code publicly whenever you "Deploy" the covered software, and "Deploy" is defined to include many kinds of private use.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Various+Licenses+and+Comments+about+Them+-+Sybase+Open+Watcom+Public+License+version+1.0+%28%23Watcom%29&rft.pub=GNU&rft_id=https%3A%2F%2Fwww.gnu.org%2Flicenses%2Flicense-list.html%23Watcom&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-fsf-32"><span class="mw-cite-backlink">^ <a href="#cite_ref-fsf_32-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-fsf_32-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.gnu.org/licenses/license-list.html#dsl">"Various Licenses and Comments about Them"</a>. GNU Project.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Various+Licenses+and+Comments+about+Them&rft.pub=GNU+Project&rft_id=https%3A%2F%2Fwww.gnu.org%2Flicenses%2Flicense-list.html%23dsl&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-33">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFEngelfriet2010" class="citation journal cs1">Engelfriet, Arnoud (2010). "Choosing an Open Source License". <i>IEEE Software</i>. <b>27</b>. Athens University of Economics and Business: 48–49. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FMS.2010.5">10.1109/MS.2010.5</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:36712745">36712745</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=IEEE+Software&rft.atitle=Choosing+an+Open+Source+License&rft.volume=27&rft.pages=48-49&rft.date=2010&rft_id=info%3Adoi%2F10.1109%2FMS.2010.5&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A36712745%23id-name%3DS2CID&rft.aulast=Engelfriet&rft.aufirst=Arnoud&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-34">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBiancuzzi2005" class="citation web cs1">Biancuzzi, Federico (30 June 2005). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20180306105402/http://www.onlamp.com/pub/a/onlamp/2005/06/30/esr_interview.html">"ESR: "We Don't Need the GPL Anymore"<span class="cs1-kern-right"></span>"</a>. ONLamp.com. Archived from <a rel="nofollow" class="external text" href="http://www.onlamp.com/pub/a/onlamp/2005/06/30/esr_interview.html">the original</a> on 6 March 2018<span class="reference-accessdate">. Retrieved <span class="nowrap">23 August</span> 2008</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ESR%3A+%22We+Don%27t+Need+the+GPL+Anymore%22&rft.pub=ONLamp.com&rft.date=2005-06-30&rft.aulast=Biancuzzi&rft.aufirst=Federico&rft_id=http%3A%2F%2Fwww.onlamp.com%2Fpub%2Fa%2Fonlamp%2F2005%2F06%2F30%2Fesr_interview.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-osi-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-osi_35-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFTiemann2006" class="citation web cs1"><a href="/wiki/Michael_Tiemann" title="Michael Tiemann">Tiemann, Michael</a> (18 September 2006). <a rel="nofollow" class="external text" href="http://www.opensource.org/licenses/alphabetical">"Licenses by Name"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">23 August</span> 2008</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Licenses+by+Name&rft.date=2006-09-18&rft.aulast=Tiemann&rft.aufirst=Michael&rft_id=http%3A%2F%2Fwww.opensource.org%2Flicenses%2Falphabetical&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-36"><span class="mw-cite-backlink"><b><a href="#cite_ref-36">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRaymond2002" class="citation web cs1"><a href="/wiki/Eric_S._Raymond" title="Eric S. Raymond">Raymond, Eric Steven</a> (9 November 2002). <a rel="nofollow" class="external text" href="http://www.catb.org/~esr/Licensing-HOWTO.html#choosing">"Licensing HOWTO"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">23 August</span> 2008</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Licensing+HOWTO&rft.date=2002-11-09&rft.aulast=Raymond&rft.aufirst=Eric+Steven&rft_id=http%3A%2F%2Fwww.catb.org%2F~esr%2FLicensing-HOWTO.html%23choosing&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-37"><span class="mw-cite-backlink"><b><a href="#cite_ref-37">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://yro.slashdot.org/comments.pl?sid=225606&cid=18272276">"What the GPLv3 Means for MS-Novell Agreement"</a>. Yro.slashdot.org. 8 March 2007<span class="reference-accessdate">. Retrieved <span class="nowrap">14 May</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=What+the+GPLv3+Means+for+MS-Novell+Agreement&rft.pub=Yro.slashdot.org&rft.date=2007-03-08&rft_id=http%3A%2F%2Fyro.slashdot.org%2Fcomments.pl%3Fsid%3D225606%26cid%3D18272276&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-38"><span class="mw-cite-backlink"><b><a href="#cite_ref-38">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFStallman2001" class="citation web cs1"><a href="/wiki/Richard_Stallman" title="Richard Stallman">Stallman, Richard</a> (26 February 2001). <a rel="nofollow" class="external text" href="https://lwn.net/2001/0301/a/rms-ov-license.php3">"LWN.net: RMS on the Ogg Vorbis license"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">23 August</span> 2008</span>. <q>[M]y agreement with the idea of a lax [Ogg/Vorbis] license in this special case is just as pragmatic as my preference for the GPL in most cases. In both cases it is a matter of how we can attain freedom.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=LWN.net%3A+RMS+on+the+Ogg+Vorbis+license&rft.date=2001-02-26&rft.aulast=Stallman&rft.aufirst=Richard&rft_id=https%3A%2F%2Flwn.net%2F2001%2F0301%2Fa%2Frms-ov-license.php3&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-39">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://news.cnet.com/2100-1001-268889.html">"Microsoft license spurns open source"</a>. <i>CNET</i>. CBS Interactive.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=CNET&rft.atitle=Microsoft+license+spurns+open+source&rft_id=http%3A%2F%2Fnews.cnet.com%2F2100-1001-268889.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-40">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation magazine cs1"><a rel="nofollow" class="external text" href="https://www.wired.co.uk/news/archive/2011-12/16/alternatives-to-copyright">"Some rights reserved: the alternatives to copyright"</a>. <i>Wired UK</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Wired+UK&rft.atitle=Some+rights+reserved%3A+the+alternatives+to+copyright&rft_id=https%3A%2F%2Fwww.wired.co.uk%2Fnews%2Farchive%2F2011-12%2F16%2Falternatives-to-copyright&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-41">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20090426091132/http://a2knetwork.org/glossary">"Glossary"</a>. <i>a2knetwork.org</i>. Archived from <a rel="nofollow" class="external text" href="http://a2knetwork.org/glossary">the original</a> on 26 April 2009.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=a2knetwork.org&rft.atitle=Glossary&rft_id=http%3A%2F%2Fa2knetwork.org%2Fglossary&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-42"><span class="mw-cite-backlink"><b><a href="#cite_ref-42">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJason_GreenbergDaniel_Glazer2013" class="citation web cs1">Jason Greenberg; Daniel Glazer (March 2013). <a rel="nofollow" class="external text" href="http://www.friedfrank.com/siteFiles/Publications/ACC-GNY_Newsletter_OpenSourceInMATransactions.pdf">"Inoculating Your Purchase – Contractual Protection from Viral Licenses in M&A Transactions"</a> <span class="cs1-format">(PDF)</span>. <i>Fried Frank</i>. Association of Corporate Counsel<span class="reference-accessdate">. Retrieved <span class="nowrap">10 June</span> 2016</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Fried+Frank&rft.atitle=Inoculating+Your+Purchase+%E2%80%93+Contractual+Protection+from+Viral+Licenses+in+M%26A+Transactions&rft.date=2013-03&rft.au=Jason+Greenberg&rft.au=Daniel+Glazer&rft_id=http%3A%2F%2Fwww.friedfrank.com%2FsiteFiles%2FPublications%2FACC-GNY_Newsletter_OpenSourceInMATransactions.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-43"><span class="mw-cite-backlink"><b><a href="#cite_ref-43">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPhilip_WoodAmy_RyburnAllan_YeomanAndrew_Matangi2013" class="citation web cs1">Philip Wood; Amy Ryburn; Allan Yeoman; Andrew Matangi; Steve Nightingale (1 July 2013). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130921110256/http://www.buddlefindlay.com/article/2013/07/01/legal-update-on-information-and-communication-technology-%E2%80%93-july-2013">"Legal update on Information and Communication Technology – July 2013"</a>. Archived from <a rel="nofollow" class="external text" href="http://www.buddlefindlay.com/article/2013/07/01/legal-update-on-information-and-communication-technology-%E2%80%93-july-2013">the original</a> on 21 September 2013<span class="reference-accessdate">. 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Retrieved <span class="nowrap">21 March</span> 2010</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Licensing+HOWTO&rft.date=2002-11-09&rft.aulast=Raymond&rft.aufirst=Eric+Steven&rft_id=http%3A%2F%2Fwww.catb.org%2F~esr%2FLicensing-HOWTO.html%23id2789302&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-not_use_LGPL-59"><span class="mw-cite-backlink"><b><a href="#cite_ref-not_use_LGPL_59-0">^</a></b></span> <span class="reference-text">Stallman, Richard. "<a rel="nofollow" class="external text" href="https://www.gnu.org/licenses/why-not-lgpl.html">Why you shouldn't use the Lesser GPL for your next library</a>". <a href="/wiki/GNU_Project" title="GNU Project">GNU Project</a>.</span> </li> <li id="cite_note-60"><span class="mw-cite-backlink"><b><a href="#cite_ref-60">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.unicode.org/charts/PDF/U1F100.pdf">"The Unicode Standard, Version 15.0: Enclosed Alphanumeric Supplement"</a> <span class="cs1-format">(PDF)</span>. <i>unicode.org</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=unicode.org&rft.atitle=The+Unicode+Standard%2C+Version+15.0%3A+Enclosed+Alphanumeric+Supplement&rft_id=https%3A%2F%2Fwww.unicode.org%2Fcharts%2FPDF%2FU1F100.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-61"><span class="mw-cite-backlink"><b><a href="#cite_ref-61">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.unicode.org/L2/L2016/16059-copyleft.pdf">"Proposal to add the Copyleft Symbol to Unicode"</a> <span class="cs1-format">(PDF)</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Proposal+to+add+the+Copyleft+Symbol+to+Unicode&rft_id=https%3A%2F%2Fwww.unicode.org%2FL2%2FL2016%2F16059-copyleft.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-UnicodePipeline-62"><span class="mw-cite-backlink">^ <a href="#cite_ref-UnicodePipeline_62-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-UnicodePipeline_62-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://unicode.org/alloc/Pipeline.html">"Proposed New Characters: Pipeline Table"</a>. <i>Unicode Character Proposals</i>. Unicode Consortium<span class="reference-accessdate">. Retrieved <span class="nowrap">18 April</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Unicode+Character+Proposals&rft.atitle=Proposed+New+Characters%3A+Pipeline+Table&rft_id=http%3A%2F%2Funicode.org%2Falloc%2FPipeline.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-63"><span class="mw-cite-backlink"><b><a href="#cite_ref-63">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://blog.unicode.org/2018/06/announcing-unicode-standard-version-110.html">"Announcing The Unicode Standard, Version 11.0"</a>. <i>The Unicode Blog</i><span class="reference-accessdate">. Retrieved <span class="nowrap">6 June</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+Unicode+Blog&rft.atitle=Announcing+The+Unicode+Standard%2C+Version+11.0&rft_id=http%3A%2F%2Fblog.unicode.org%2F2018%2F06%2Fannouncing-unicode-standard-version-110.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-64"><span class="mw-cite-backlink"><b><a href="#cite_ref-64">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHall2008" class="citation book cs1">Hall, G. Brent (2008). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=JZNuu8XODQMC&pg=PA29"><i>Open Source Approaches in Spatial Data Handling</i></a>. Springer. p. 29. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2008osas.book.....H">2008osas.book.....H</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9783540748311" title="Special:BookSources/9783540748311"><bdi>9783540748311</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Open+Source+Approaches+in+Spatial+Data+Handling&rft.pages=29&rft.pub=Springer&rft.date=2008&rft_id=info%3Abibcode%2F2008osas.book.....H&rft.isbn=9783540748311&rft.aulast=Hall&rft.aufirst=G.+Brent&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DJZNuu8XODQMC%26pg%3DPA29&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> <li id="cite_note-65"><span class="mw-cite-backlink"><b><a href="#cite_ref-65">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.compart.com/en/unicode/U+1F12F">"Unicode Character "🄯" (U+1F12F)"</a>. <i>www.compart.com</i><span class="reference-accessdate">. Retrieved <span class="nowrap">12 September</span> 2024</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.compart.com&rft.atitle=Unicode+Character+%22%F0%9F%84%AF%22+%28U%2B1F12F%29&rft_id=https%3A%2F%2Fwww.compart.com%2Fen%2Funicode%2FU%2B1F12F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACopyleft" class="Z3988"></span></span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Copyleft&action=edit&section=18" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Commons-logo.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/12px-Commons-logo.svg.png" decoding="async" width="12" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/18px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/24px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></a></span> Media related to <a href="https://commons.wikimedia.org/wiki/Category:Copyleft" class="extiw" title="commons:Category:Copyleft">Copyleft</a> at Wikimedia Commons</li> <li><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Wiktionary-logo-en-v2.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/16px-Wiktionary-logo-en-v2.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/24px-Wiktionary-logo-en-v2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/32px-Wiktionary-logo-en-v2.svg.png 2x" data-file-width="512" data-file-height="512" /></a></span> The dictionary definition of <a href="https://en.wiktionary.org/wiki/copyleft" class="extiw" title="wiktionary:copyleft"><i>copyleft</i></a> at Wiktionary</li></ul> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output 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rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:FOSS" title="Template:FOSS"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:FOSS" title="Template talk:FOSS"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:FOSS" title="Special:EditPage/Template:FOSS"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Free_and_open-source_software" style="font-size:114%;margin:0 4em"><a href="/wiki/Free_and_open-source_software" title="Free and open-source software">Free and open-source software</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">General</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Alternative_terms_for_free_software" title="Alternative terms for free software">Alternative terms for free software</a></li> <li><a href="/wiki/Comparison_of_open-source_and_closed-source_software" title="Comparison of open-source and closed-source software">Comparison of open-source and closed-source software</a></li> <li><a href="/wiki/Comparison_of_source-code-hosting_facilities" title="Comparison of source-code-hosting facilities">Comparison of source-code-hosting facilities</a></li> <li><a href="/wiki/Free_software" title="Free software">Free software</a></li> <li><a href="/wiki/List_of_free_software_project_directories" title="List of free software project directories">Free software project directories</a></li> <li><a href="/wiki/Gratis_versus_libre" title="Gratis versus libre">Gratis versus libre</a></li> <li><a href="/wiki/Long-term_support" title="Long-term support">Long-term support</a></li> <li><a href="/wiki/Open-source_software" title="Open-source software">Open-source software</a></li> <li><a href="/wiki/Open-source_software_development" title="Open-source software development">Open-source software development</a></li> <li><a href="/wiki/Outline_of_free_software" title="Outline of free software">Outline</a></li> <li><a href="/wiki/Timeline_of_free_and_open-source_software" title="Timeline of free and open-source software">Timeline</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/List_of_free_and_open-source_software_packages" title="List of free and open-source software packages">Software<br />packages</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Comparison_of_free_software_for_audio" title="Comparison of free software for audio">Audio</a></li> <li><a href="/wiki/List_of_open-source_bioinformatics_software" title="List of open-source bioinformatics software">Bioinformatics</a></li> <li><a href="/wiki/List_of_open-source_codecs" title="List of open-source codecs">Codecs</a></li> <li><a href="/wiki/Comparison_of_open-source_configuration_management_software" title="Comparison of open-source configuration management software">Configuration management</a></li> <li><a href="/wiki/Device_driver" title="Device driver">Drivers</a> <ul><li><a href="/wiki/Free_and_open-source_graphics_device_driver" title="Free and open-source graphics device driver">Graphics</a></li> <li><a href="/wiki/Comparison_of_open-source_wireless_drivers" title="Comparison of open-source wireless drivers">Wireless</a></li></ul></li> <li><a href="/wiki/List_of_open-source_health_software" title="List of open-source health software">Health</a></li> <li><a href="/wiki/List_of_open-source_software_for_mathematics" title="List of open-source software for mathematics">Mathematics</a></li> <li><a href="/wiki/List_of_office_suites" title="List of office suites">Office suites</a></li> <li><a href="/wiki/Comparison_of_open-source_operating_systems" title="Comparison of open-source operating systems">Operating systems</a></li> <li><a href="/wiki/List_of_open-source_routing_platforms" title="List of open-source routing platforms">Routing</a></li> <li><a href="/wiki/List_of_free_television_software" title="List of free television software">Television</a></li> <li><a href="/wiki/List_of_open-source_video_games" title="List of open-source video games">Video games</a></li> <li><a href="/wiki/List_of_free_and_open-source_web_applications" title="List of free and open-source web applications">Web applications</a> <ul><li><a href="/wiki/Comparison_of_shopping_cart_software" title="Comparison of shopping cart software">E-commerce</a></li></ul></li> <li><a href="/wiki/List_of_free_and_open-source_Android_applications" title="List of free and open-source Android applications">Android apps</a></li> <li><a href="/wiki/List_of_free_and_open-source_iOS_applications" title="List of free and open-source iOS applications">iOS apps</a></li> <li><a href="/wiki/List_of_commercial_open-source_applications_and_services" title="List of commercial open-source applications and services">Commercial</a></li> <li><a href="/wiki/List_of_formerly_proprietary_software" title="List of formerly proprietary software">Formerly proprietary</a></li> <li><a href="/wiki/List_of_formerly_free_and_open-source_software" class="mw-redirect" title="List of formerly free and open-source software">Formerly open-source</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Community_of_practice" title="Community of practice">Community</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Free_software_movement" title="Free software movement">Free software movement</a></li> <li><a href="/wiki/History_of_free_and_open-source_software" title="History of free and open-source software">History</a></li> <li><a href="/wiki/Open-source-software_movement" title="Open-source-software movement">Open-source-software movement</a></li> <li><a href="/wiki/List_of_free-software_events" title="List of free-software events">Events</a></li> <li><a href="/wiki/Open-source_software_advocacy" title="Open-source software advocacy">Advocacy</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/List_of_free_and_open-source_software_organizations" title="List of free and open-source software organizations">Organisations</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Free_Software_Movement_of_India" title="Free Software Movement of India">Free Software Movement of India</a></li> <li><a href="/wiki/Free_Software_Foundation" title="Free Software Foundation">Free Software Foundation</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Free-software_license" title="Free-software license">Licenses</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Academic_Free_License" title="Academic Free License">AFL</a></li> <li><a href="/wiki/Apache_License" title="Apache License">Apache</a></li> <li><a href="/wiki/Apple_Public_Source_License" title="Apple Public Source License">APSL</a></li> <li><a href="/wiki/Artistic_License" title="Artistic License">Artistic</a></li> <li><a href="/wiki/Beerware" title="Beerware">Beerware</a></li> <li><a href="/wiki/BSD_licenses" title="BSD licenses">BSD</a></li> <li><a href="/wiki/Creative_Commons_license" title="Creative Commons license">Creative Commons</a></li> <li><a href="/wiki/Common_Development_and_Distribution_License" title="Common Development and Distribution License">CDDL</a></li> <li><a href="/wiki/Eclipse_Public_License" title="Eclipse Public License">EPL</a></li> <li><a href="/wiki/Free_Software_Foundation" title="Free Software Foundation">Free Software Foundation</a> <ul><li><a href="/wiki/GNU_General_Public_License" title="GNU General Public License">GNU GPL</a></li> <li><a href="/wiki/GNU_Affero_General_Public_License" title="GNU Affero General Public License">GNU AGPL</a></li> <li><a href="/wiki/GNU_Lesser_General_Public_License" title="GNU Lesser General Public License">GNU LGPL</a></li></ul></li> <li><a href="/wiki/ISC_license" title="ISC license">ISC</a></li> <li><a href="/wiki/MIT_License" title="MIT License">MIT</a></li> <li><a href="/wiki/Mozilla_Public_License" title="Mozilla Public License">MPL</a></li> <li><a href="/wiki/Python_License" title="Python License">Python</a></li> <li><a href="/wiki/Python_Software_Foundation_License" title="Python Software Foundation License">Python Software Foundation License</a></li> <li><a href="/wiki/Shared_Source_Initiative" title="Shared Source Initiative">Shared Source Initiative</a></li> <li><a href="/wiki/Sleepycat_License" class="mw-redirect" title="Sleepycat License">Sleepycat</a></li> <li><a href="/wiki/Unlicense" title="Unlicense">Unlicense</a></li> <li><a href="/wiki/WTFPL" title="WTFPL">WTFPL</a></li> <li><a href="/wiki/Zlib_License" title="Zlib License">zlib</a></li></ul> </div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th id="Types_and_standards" scope="row" class="navbox-group" style="width:1%">Types and<br /> standards</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Comparison_of_free_and_open-source_software_licenses" title="Comparison of free and open-source software licenses">Comparison of licenses</a></li> <li><a href="/wiki/Contributor_License_Agreement" title="Contributor License Agreement">Contributor License Agreement</a></li> <li><a class="mw-selflink selflink">Copyleft</a></li> <li><a href="/wiki/Debian_Free_Software_Guidelines" class="mw-redirect" title="Debian Free Software Guidelines">Debian Free Software Guidelines</a></li> <li><a href="/wiki/Definition_of_Free_Cultural_Works" title="Definition of Free Cultural Works">Definition of Free Cultural Works</a></li> <li><a href="/wiki/Free_license" title="Free license">Free license</a></li> <li><a href="/wiki/The_Free_Software_Definition" title="The Free Software Definition">The Free Software Definition</a></li> <li><a href="/wiki/The_Open_Source_Definition" title="The Open Source Definition">The Open Source Definition</a></li> <li><a href="/wiki/Open-source_license" title="Open-source license">Open-source license</a></li> <li><a href="/wiki/Permissive_software_license" title="Permissive software license">Permissive software license</a></li> <li><a href="/wiki/Public_domain" title="Public domain">Public domain</a></li></ul> </div></td></tr></tbody></table><div> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Challenges</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Digital_rights_management" title="Digital rights management">Digital rights management</a></li> <li><a href="/wiki/License_proliferation" title="License proliferation">License proliferation</a></li> <li><a href="/wiki/Mozilla_software_rebranded_by_Debian" class="mw-redirect" title="Mozilla software rebranded by Debian">Mozilla software rebranding</a></li> <li><a href="/wiki/Proprietary_device_driver" class="mw-redirect" title="Proprietary device driver">Proprietary device drivers</a></li> <li><a href="/wiki/Proprietary_firmware" title="Proprietary firmware">Proprietary firmware</a></li> <li><a href="/wiki/Proprietary_software" title="Proprietary software">Proprietary software</a></li> <li><a href="/wiki/SCO%E2%80%93Linux_disputes" title="SCO–Linux disputes">SCO/Linux controversies</a></li> <li><a href="/wiki/Software_patents_and_free_software" title="Software patents and free software">Software patents</a></li> <li><a href="/wiki/Open-source_software_security" title="Open-source software security">Software security</a></li> <li><a href="/wiki/Tivoization" title="Tivoization">Tivoization</a></li> <li><a href="/wiki/Trusted_Computing" title="Trusted Computing">Trusted Computing</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related <br />topics</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Fork_(software_development)" title="Fork (software development)">Forking</a></li> <li><i><a href="/wiki/GNU_Manifesto" title="GNU Manifesto">GNU Manifesto</a></i></li> <li><a href="/wiki/Microsoft_Open_Specification_Promise" title="Microsoft Open Specification Promise">Microsoft Open Specification Promise</a></li> <li><a href="/wiki/Open-core_model" title="Open-core model">Open-core model</a></li> <li><a href="/wiki/Open-source_hardware" title="Open-source hardware">Open-source hardware</a></li> <li><a href="/wiki/Shared_Source_Initiative" title="Shared Source Initiative">Shared Source Initiative</a></li> <li><a href="/wiki/Source-available_software" title="Source-available software">Source-available software</a></li> <li><i><a href="/wiki/The_Cathedral_and_the_Bazaar" title="The Cathedral and the Bazaar">The Cathedral and the Bazaar</a></i></li> <li><i><a href="/wiki/Revolution_OS" title="Revolution OS">Revolution OS</a></i></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2" style="font-weight:bold"><div> <ul><li><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Symbol_portal_class.svg" class="mw-file-description" title="Portal"><img alt="" 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//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <a href="/wiki/Category:Free_software" title="Category:Free software">Category</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Intellectual_property_activism" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Intellectual_property_activism" title="Template:Intellectual property activism"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Intellectual_property_activism" title="Template talk:Intellectual property activism"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Intellectual_property_activism" title="Special:EditPage/Template:Intellectual property activism"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Intellectual_property_activism" style="font-size:114%;margin:0 4em"><a href="/wiki/Intellectual_property" title="Intellectual property">Intellectual property</a> activism</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Issues</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Artificial_scarcity" title="Artificial scarcity">Artificial scarcity</a></li> <li><a href="/wiki/Censorship_by_copyright" title="Censorship by copyright">Censorship by copyright</a></li> <li><a href="/wiki/Copyright_infringement" title="Copyright infringement">Copyright infringement</a></li> <li><a href="/wiki/Copyright_troll" title="Copyright troll">Copyright troll</a></li> <li><a href="/wiki/Digital_rights_management" title="Digital rights management">Digital rights management</a></li> <li><a href="/wiki/Gripe_site" title="Gripe site">Gripe site</a></li> <li><a href="/wiki/Legal_aspects_of_file_sharing" title="Legal aspects of file sharing">Legal aspects of file sharing</a></li> <li><a href="/wiki/Mashup_(culture)" title="Mashup (culture)">Mashup</a> <ul><li><a href="/wiki/Mashup_(web_application_hybrid)" title="Mashup (web application hybrid)">digital</a></li> <li><a href="/wiki/Mashup_(music)" title="Mashup (music)">music</a></li> <li><a href="/wiki/Mashup_novel" title="Mashup novel">novel</a></li> <li><a href="/wiki/Mashup_(video)" title="Mashup (video)">videos</a></li></ul></li> <li><a href="/wiki/Monopolies_of_knowledge" title="Monopolies of knowledge">Monopolies of knowledge</a></li> <li><a href="/wiki/Music_piracy" title="Music piracy">Music piracy</a></li> <li><a href="/wiki/Orphan_work" title="Orphan work">Orphan works</a></li> <li><a href="/wiki/Biopiracy" title="Biopiracy">Biopiracy</a> <ul><li><a href="/wiki/Bioprospecting" title="Bioprospecting">Bioprospecting</a></li></ul></li> <li><a href="/wiki/Societal_views_on_patents" class="mw-redirect" title="Societal views on patents">Patents</a> <ul><li><a href="/wiki/Biological_patent" title="Biological patent">biological</a></li> <li><a href="/wiki/Software_patent" title="Software patent">software</a></li> <li><a href="/wiki/Software_patent_debate" title="Software patent debate">software patent debate</a></li> <li><a href="/wiki/Patent_troll" title="Patent troll">trolling</a></li></ul></li> <li><a href="/wiki/Public_domain" title="Public domain">Public domain</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Concepts</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/All_rights_reversed" title="All rights reversed">All rights reversed</a></li> <li><a href="/wiki/Copyright_alternatives" title="Copyright alternatives">Alternative compensation system</a></li> <li><a href="/wiki/Anti-copyright_notice" title="Anti-copyright notice">Anti-copyright notice</a></li> <li><a href="/wiki/Business_models_for_open-source_software" title="Business models for open-source software">Business models for open-source software</a></li> <li><a class="mw-selflink selflink">Copyleft</a></li> <li><a href="/wiki/Commercial_use_of_copyleft_works" title="Commercial use of copyleft works">Commercial use of copyleft works</a></li> <li><a href="/wiki/Commons-based_peer_production" title="Commons-based peer production">Commons-based peer production</a></li> <li><a href="/wiki/Electronic_sell-through" title="Electronic sell-through">Electronic sell-through</a></li> <li><a href="/wiki/Free_content" title="Free content">Free content</a></li> <li><a href="/wiki/Free-software_license" title="Free-software license">Free-software license</a></li> <li><a href="/wiki/Libertarian_perspectives_on_intellectual_property" title="Libertarian perspectives on intellectual property">Libertarian positions</a></li> <li><a href="/wiki/Open_content" class="mw-redirect" title="Open content">Open content</a></li> <li><a href="/wiki/Open-design_movement" title="Open-design movement">Open-design movement</a></li> <li><a href="/wiki/Open_music_model" title="Open music model">Open music model</a></li> <li><a href="/wiki/Patentleft" title="Patentleft">Open patent</a></li> <li><a href="/wiki/Open_source" title="Open source">Open source</a> <ul><li><a href="/wiki/Open-source_hardware" title="Open-source hardware">hardware</a></li> <li><a href="/wiki/Open-source_software" title="Open-source software">software</a></li></ul></li> <li><a href="/wiki/Prizes_as_an_alternative_to_patents" title="Prizes as an alternative to patents">Prizes instead of patents</a> <ul><li><a href="/wiki/Inducement_prize_contest" title="Inducement prize contest">contests</a></li></ul></li> <li><a href="/wiki/Share-alike" title="Share-alike">Share-alike</a></li> <li><a href="/wiki/Video_on_demand" title="Video on demand">Video on demand</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Movements</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Access_to_Knowledge_movement" title="Access to Knowledge movement">Access to Knowledge movement</a></li> <li><a href="/wiki/Criticism_of_copyright" title="Criticism of copyright">Anti-copyright</a></li> <li><a href="/wiki/Cultural_environmentalism" title="Cultural environmentalism">Cultural environmentalism</a></li> <li><a href="/wiki/Free-culture_movement" title="Free-culture movement">Free-culture movement</a></li> <li><a href="/wiki/Free_software_movement" title="Free software movement">Free software movement</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Organizations</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Pro-copyright</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Copyright_Alliance" title="Copyright Alliance">Copyright Alliance</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Pro-copyleft</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Creative_Commons" title="Creative Commons">Creative Commons</a></li> <li><a href="/wiki/Electronic_Frontier_Foundation" title="Electronic Frontier Foundation">Electronic Frontier Foundation</a></li> <li><a href="/wiki/Free_Software_Foundation" title="Free Software Foundation">Free Software Foundation</a></li> <li><a href="/wiki/Open_Rights_Group" title="Open Rights Group">Open Rights Group</a></li> <li><a href="/wiki/Organization_for_Transformative_Works" title="Organization for Transformative Works">Organization for Transformative Works</a></li> <li><a href="/wiki/The_Pirate_Bay" title="The Pirate Bay">The Pirate Bay</a></li> <li><a href="/wiki/Piratbyr%C3%A5n" title="Piratbyrån">Piratbyrån</a></li> <li><a href="/wiki/Pirate_Party" title="Pirate Party">Pirate Party</a></li> <li><a href="/wiki/Public_Knowledge" title="Public Knowledge">Public Knowledge</a></li> <li><a href="/wiki/Sci-Hub" title="Sci-Hub">Sci-Hub</a></li> <li><a href="/wiki/Shadow_library" title="Shadow library">Shadow library</a></li> <li><a href="/wiki/Students_for_Free_Culture" title="Students for Free Culture">Students for Free Culture</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">People</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cory_Doctorow" title="Cory Doctorow">Cory Doctorow</a></li> <li><a href="/wiki/Alexandra_Elbakyan" title="Alexandra Elbakyan">Alexandra Elbakyan</a></li> <li><a href="/wiki/Rick_Falkvinge" title="Rick Falkvinge">Rick Falkvinge</a></li> <li><a href="/wiki/Lawrence_Lessig" title="Lawrence Lessig">Lawrence Lessig</a></li> <li><a href="/wiki/Richard_Stallman" title="Richard Stallman">Richard Stallman</a></li> <li><a href="/wiki/Peter_Suber" title="Peter Suber">Peter Suber</a></li> <li><a href="/wiki/Peter_Sunde" title="Peter Sunde">Peter Sunde</a></li> <li><a href="/wiki/Aaron_Swartz" title="Aaron Swartz">Aaron Swartz</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Documentaries</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><i><a href="/wiki/Steal_This_Film" title="Steal This Film">Steal This Film</a></i></li> <li><i><a href="/wiki/Good_Copy_Bad_Copy" title="Good Copy Bad Copy">Good Copy Bad Copy</a></i></li> <li><i><a href="/wiki/RiP!:_A_Remix_Manifesto" title="RiP!: A Remix Manifesto">RiP!: A Remix Manifesto</a></i></li> <li><i><a href="/wiki/TPB_AFK" title="TPB AFK">TPB AFK</a></i></li> <li><i><a href="/wiki/The_Internet%27s_Own_Boy" title="The Internet's Own Boy">The Internet's Own Boy</a></i></li></ul> 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