CINXE.COM

<!DOCTYPE html> <html id="homeTemplate_1-0" class="comp homeTemplate html mntl-html no-js taxlevel-0" data-ab="99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,78,99" data-mm-ads-resource-version="2.1.35" data-reference-resource-version="5.14.0" data-mm-video-resource-version="2.1.7" data-mantle-resource-version="4.1.104" lang="en" data-tracking-container="true" data-resource-version="5.14.0" data-ddm-standard-tracking="true"> <head class="loc head"> <link rel="preconnect" href="//js-sec.indexww.com"> <link rel="preconnect" href="//c.amazon-adsystem.com"> <link rel="preconnect" href="//securepubads.g.doubleclick.net"> <link rel="dnsprefetch" href="//www.google-analytics.com"> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="robots" content="max-image-preview:large, NOODP, NOYDIR" /> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <link rel="canonical" href="https://www.thoughtco.com/" /> <title>ThoughtCo.com is the World's Largest Education Resource</title> <meta name="description" content="From chemistry to computer programming, arts to World War II, ThoughtCo.com provides guides, tips, and resources to help you understand more about the world around us." itemprop="description"> <meta name="emailvertical" content="THOUGHTCO" />  <meta itemprop="name" content="ThoughtCo.com is the World's Largest Education Resource" /> <meta property="article:section" content="ThoughtCo" />  <meta property="og:type" content="website" /> <meta property="og:site_name" content="ThoughtCo" /> <meta property="og:url" content="https://www.thoughtco.com/" /> <meta property="og:title" content="ThoughtCo.com is the World's Largest Education Resource" /> <meta property="og:description" content="From chemistry to computer programming, arts to World War II, ThoughtCo.com provides guides, tips, and resources to help you understand more about the world around us." /> <meta property="og:image" content="https://www.thoughtco.com/thmb/WjSg5aGyHogR9T18eCi4vdFEwj0=/1500x0/filters:no_upscale():max_bytes(150000):strip_icc()/thoughtCo_pin_img_default-58a21e1638e9b32984d5b865.png" /> <meta property="article:author" content="https://www.facebook.com/thoughtcodotcom/" />  <meta name="twitter:card" content="summary_large_image" /> <meta name="twitter:site" content="@thoughtcocom" /> <meta name="twitter:title" content="ThoughtCo.com is the World's Largest Education Resource" /> <meta name="twitter:description" content="From chemistry to computer programming, arts to World War II, ThoughtCo.com provides guides, tips, and resources to help you understand more about the world around us." /> <meta name="twitter:image" content="https://www.thoughtco.com/thmb/WjSg5aGyHogR9T18eCi4vdFEwj0=/1500x0/filters:no_upscale():max_bytes(150000):strip_icc()/thoughtCo_pin_img_default-58a21e1638e9b32984d5b865.png" /> <link rel="alternate" type="application/rss+xml" href="https://feeds-api.dotdashmeredith.com/v1/rss/google/e5bf8ae1-a904-434a-842c-3487c2b4e7c2"> <link type="text/css" rel="stylesheet" data-glb-css="top" href="/static/5.14.0/cache/eNqdVVuWnCAQ3VA4LiK_2UQJpVYEygD2THYfHo6tLUd68iO3Hre4VNF05wMEkp0BGzR20vsuefBHdw2QgRHFokHixFqhqyUZdKQIbEdW4eeekUNA9uSY2OASa17qsFnYog2-m6OWz_J9Ul_DDgd0aCWKc6JhtWr0R4ID0uJBCjkryOguvwe_dUUKUL6mIbq7Y-h6iA9SI8bVcqCBZMxiK3qwFl1pLG7WGzUmpHEKPyewI_4iHzAVqTlrUkfNPeiYDiqzQNXzLDxozDI7P9MiNNn5iWqMgZ2J9dPGoIVHcHJ6MRsbFTUieg6wwRlWrb10iDbzzmaD27u4i3Sr6f0RN1iSbQAZ8nYH3GD9Xs3WxB3djHqb0sAc4pTKcjPNet617HGoLCnOJR8i3e3dbF2GJ6_Cud2yyCtj2uG3qKlr_mS8R1ccFPhJrJYe6Pymv-ptHL88gIm9oxsJOSf3d6ShVtmjTGXj6-FiRKOQrFdztWtcHX_l8d5qlrNI-ABr6Tm6LeXbmvTCQadH5Ym-zxAfFCYRKDbm7o31f1ZwX_89JOe_onje5ZyTm-pK119kvX-m0sr_IKbZ_APV0N4E.min.css"></link> <style type="text/css"> </style> <script type="text/javascript" data-glb-js="top" src="/static/5.14.0/cache/eNp9kmFqwzAMhS80kzNsMPZrMEYuoNhKqsaxgiW3tKefEwpNOzUQB8vvs2T7qREFJd9MkDRi43maOWFSaSJcuGhzlPo5f0A_vjWP8HGBrhehK1aCU0_DM3KLInXyiFNSzIJeiZOVlyFgMATPPBKKoRSlSGprfXJ7cuBpV9cMfqQ07EInTIFzo4fMWpcMYqoT12WEceZ6_3uSqmXsMWPy-LrGxhsvuV9_RpW5dFK6u8ChRFxf_7f9WMYrab1lnXyecHu4zfnh0qG1G8LNfgczPUY2_o2ayUu7VMRsMmVtDddH5vwcWhu-ftplWJJCHlAX_wR6jCRqUeIdBDN1xvoiBdtbF1jIf9M2btW0CzPMatkFA7oT4XnH7kGntfcj-dHpzjFqF2WUA3QR34P8AUAAdAA.min.js"></script> <script type="text/javascript"> window.Mntl = window.Mntl || {}; window.Mntl.csrf = window.Mntl.csrf || window.Mntl.csrfInit('0766e2aad9bb56a5d9de5fe257d68a18', false);window.Mntl = window.Mntl || {}; Mntl.RTB = Mntl.RTB || {}; Mntl.RTB.setUseConsentManagement(false); Mntl.RTB.setIpAddress('8.222.208.146') Mntl.RTB.setUseLiveIntentSignedInUser(true); Mntl.RTB.setUseGDPREnforcement(false); Mntl.RTB.setUseCommerceAndShoppingAPSTag(false); Mntl.RTB.setUseAmazonNcaHookTest(false); Mntl.RTB.setTaxonomyStampValues({"tax0":"tho_root"}); Mntl.RTB.setPrebidBidResponseTimeout(950); Mntl.RTB.setPrebidUserIdAuctionDelay(500); Mntl.RTB.setRtbLibraryLoadTimeout(750); Mntl.RTB.setAmazonTamBidResponseTimeout(1000); Mntl.RTB.Plugins.amazon.amazonConfigs = {"mapTaxValues":{"tax1":"null","tax2":"null","si_section":"null","tax0":"tho_root","tax3":"null"},"amazonSlotName":false,"mapFBValues":{"billboard2":"287662961980198_287667961979698","billboard6":"287662961980198_287667961979698","adunitid":"mapFBID","billboard5":"287662961980198_287667961979698","billboard4":"287662961980198_287667961979698","billboard3":"287662961980198_287667961979698","leaderboard2":"287662961980198_287667635313064","billboard7":"287662961980198_287667961979698","video":"287662961980198_287667961979698","billboard":"287662961980198_287667961979698","leaderboardac":"287662961980198_287667961979698","leaderboard":"287662961980198_287668258646335","default":"287662961980198_287667961979698","leaderboardfooter2":"287662961980198_287667961979698","native":"287662961980198_287667961979698","leaderboardfooter":"287662961980198_287667635313064"}}; Mntl.RTB.Plugins.prebid.setPriceGranularity({"buckets":[{"max":"20","increment":"0.05"},{"max":"70","increment":"1"}]}); Mntl.RTB.initVideoBidders([{ type: 'amazon', id: '3222' }, { type: 'prebid', id: 'true' } ]); Mntl.RTB.initDisplayAndOutstreamBidders([{ type: "amazon", id: '3222'},{ type: "msg", id: 'true'},{ type: "prebid", id: 'true'},{ type: "liveConnect", id: 'b-01jb'}]); Mntl.RTB.Plugins.prebid.setConfig({"square-fixed\/tier1":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442664,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482890,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"4515221","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_square-fixed_300x250_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324010","type":"display"}},{"bidder":"ix","params":{"siteId":"830375","type":"display"}}],"leaderboard-fixed\/tier1":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442654,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482885,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"4515375","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_leaderboard-fixed_728x90_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324000","type":"display"}},{"bidder":"ix","params":{"siteId":"830371","type":"display"}}],"square-fixed-replies\/tier1":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":3601290,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":34330401,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"6389437","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"thoughtco_square-fixed-replies_300x250_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561381983","type":"display"}},{"bidder":"ix","params":{"siteId":"1146794","type":"display"}}],"preroll":[{"bidder":"ttd","params":{"type":"instream","supplySourceId":"dotdash","publisherId":"1"}},{"bidder":"rubicon","params":{"type":"instream","zoneId":2442674,"accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"type":"instream","placementId":25482895}},{"bidder":"pubmatic","params":{"type":"instream","publisherId":"158139","adSlot":"4515226"}},{"bidder":"triplelift","params":{"type":"instream","inventoryCode":"ThoughtCo_preroll_pbc2s"}},{"bidder":"openx","params":{"type":"instream","delDomain":"meredith-d.openx.net","unit":"561365587"}},{"bidder":"ix","params":{"type":"instream","siteId":"830386"}}],"square-flex\/tier1":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442672,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482894,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"4515225","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_square-flex_300x600_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324012","type":"display"}},{"bidder":"ix","params":{"siteId":"830381","type":"display"}}],"square-fixed-comments\/tier1":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":3546588,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":34080851,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"6234514","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"thoughtco_square-fixed-comments_300x250_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324013","type":"display"}},{"bidder":"ix","params":{"siteId":"1137158","type":"display"}}],"global":[{"bidder":"rubicon","params":{"accountId":7499,"siteId":426884,"type":"display"}}],"native\/tier1":[{"bidder":"rubicon","params":{"zoneId":3700118,"type":"display","accountId":7499,"siteId":426884}}],"leaderboardac\/tier1":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442662,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482889,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"6405120","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_leaderboardac_728x90_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324006","type":"display"}},{"bidder":"ix","params":{"siteId":"830377","type":"display"}}],"leaderboardfooter-flex\/tier1":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442654,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482885,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"4632121","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_leaderboardfooter-flex_970x250_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324008","type":"display"}},{"bidder":"ix","params":{"siteId":"830371","type":"display"}}],"leaderboard-flex\/tier1":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442662,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482889,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"4515220","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_leaderboard-flex_970x250_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324003","type":"display"}},{"bidder":"ix","params":{"siteId":"830377","type":"display"}}]}); Mntl.RTB.Plugins.prebid.setSrc('/cache/eNqlllGP0zAMx78Q08RJfIABu9NJTBy3wXuauD3fUjtynG3l0-PtEOIFqS5PbSP_HMdO_fe6alCM65FTy1DXXaN0fb7WdRHoMNlLwqq_v1aRBd6t50IhZz5vouIJFaE6QK0bCnky47pJoSjIfDgyEUR9TPupKowusALpLlAYYLS3Q-wdtKAC-3dN0LVhQBocSF82aQ9yAvmBCXg-OQCBYFyeXAz1WdOT8Mk29nDpgz81tgUp6vQF6einM57gkdRc-NkSQsF7loeiTshjjrIgstvXW_E_YnIXsFj54T4zi-N_FE27m818pL4EgeQ_n8b-E5MK5_lMw3Tn36kR9rgkxFbBCufoZqUQXFpdUi68LCpy68ar5RJWWofWCZegqmkRJlgyZOx1Cc0FaFGS4kujo1PRBgFIk0cUwAxPsBIg65cgK1suOThchOVCOJb_ED9HUop-V8zVJWBO4jJmJ1HxJzgR6yPvt5h8xJ2P-FuVHNVpYjcoTs4DnSEc9-q64SzaWQM2dfF1nK5uL3aqinaPHL8-jsBNvzVonhi7VxvwHloQRwoTjwHpqx1MbK448DOzfr6tzfdxhOnM4in3rcn4pcJZ5xgUBpbpIIFqNoZpZ65cQ6Ve2Z5lfAoSRm8EV03cTxS9gb_N6hbvI_WOObbJP9rBH8vtBWK7Ov4Fwmrvsg.js'); Mntl.RTB.Plugins.prebid.setUserIdConfig({"liveIntentPublisherId":"79925"}); window.MMads = window.MMads || {}; MMads.adConfigAPI = MMads.adConfigAPI || {}; // prebidConfig MMads.adConfigAPI.AdConfigs = MMads.adConfigAPI.AdConfigs || {}; MMads.adConfigAPI.AdConfigs.rawConfig = {"slots":{"square-fixed\/tier1":{"prebid":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442664,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482890,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"4515221","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_square-fixed_300x250_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324010","type":"display"}},{"bidder":"ix","params":{"siteId":"830375","type":"display"}}]},"native\/tier1":{"prebid":[{"bidder":"rubicon","params":{"zoneId":3700118,"type":"display","accountId":7499,"siteId":426884}}]},"square-flex\/tier1":{"prebid":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442672,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482894,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"4515225","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_square-flex_300x600_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324012","type":"display"}},{"bidder":"ix","params":{"siteId":"830381","type":"display"}}]},"preroll":{"prebid":[{"bidder":"ttd","params":{"type":"instream","supplySourceId":"dotdash","publisherId":"1"}},{"bidder":"rubicon","params":{"type":"instream","zoneId":2442674,"accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"type":"instream","placementId":25482895}},{"bidder":"pubmatic","params":{"type":"instream","publisherId":"158139","adSlot":"4515226"}},{"bidder":"triplelift","params":{"type":"instream","inventoryCode":"ThoughtCo_preroll_pbc2s"}},{"bidder":"openx","params":{"type":"instream","delDomain":"meredith-d.openx.net","unit":"561365587"}},{"bidder":"ix","params":{"type":"instream","siteId":"830386"}}]},"square-fixed-replies\/tier1":{"prebid":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":3601290,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":34330401,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"6389437","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"thoughtco_square-fixed-replies_300x250_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561381983","type":"display"}},{"bidder":"ix","params":{"siteId":"1146794","type":"display"}}]},"leaderboard-fixed\/tier1":{"prebid":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442654,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482885,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"4515375","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_leaderboard-fixed_728x90_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324000","type":"display"}},{"bidder":"ix","params":{"siteId":"830371","type":"display"}}]},"leaderboard-flex\/tier1":{"prebid":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442662,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482889,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"4515220","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_leaderboard-flex_970x250_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324003","type":"display"}},{"bidder":"ix","params":{"siteId":"830377","type":"display"}}]},"leaderboardfooter-flex\/tier1":{"prebid":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442654,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482885,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"4632121","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_leaderboardfooter-flex_970x250_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324008","type":"display"}},{"bidder":"ix","params":{"siteId":"830371","type":"display"}}]},"square-fixed-comments\/tier1":{"prebid":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":3546588,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":34080851,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"6234514","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"thoughtco_square-fixed-comments_300x250_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324013","type":"display"}},{"bidder":"ix","params":{"siteId":"1137158","type":"display"}}]},"leaderboardac\/tier1":{"prebid":[{"bidder":"ttd","params":{"supplySourceId":"dotdash","publisherId":"1","type":"display"}},{"bidder":"rubicon","params":{"zoneId":2442662,"type":"display","accountId":7499,"siteId":426884}},{"bidder":"appnexus","params":{"placementId":25482889,"type":"display"}},{"bidder":"pubmatic","params":{"publisherId":"158139","adSlot":"6405120","type":"display"}},{"bidder":"triplelift","params":{"inventoryCode":"ThoughtCo_leaderboardac_728x90_pbc2s","type":"display"}},{"bidder":"openx","params":{"delDomain":"meredith-d.openx.net","unit":"561324006","type":"display"}},{"bidder":"ix","params":{"siteId":"830377","type":"display"}}]}},"default":{"prebid":[{"bidder":"rubicon","params":{"accountId":7499,"siteId":426884,"type":"display"}}],"prebidModules":["prebid-core.js","allowActivities.js","atsAnalyticsAdapter.js","connectIdSystem.js","consentManagementTcf.js","criteoIdSystem.js","debugging.js","dfpAdServerVideo.js","genericAnalyticsAdapter.js","iasRtdProvider.js","id5IdSystem.js","identityLinkIdSystem.js","liveIntentIdSystem.js","paapiForGpt.js","paapi.js","pairIdSystem.js","prebidServerBidAdapter.js","priceFloors.js","rtdModule.js","sharedIdSystem.js","tcfControl.js","uid2IdSystem.js","unifiedIdSystem.js","userId.js","appnexusBidAdapter.js","ixBidAdapter.js","pubmaticBidAdapter.js","rubiconBidAdapter.js","ttdBidAdapter.js","tripleliftBidAdapter.js","openxBidAdapter.js"],"refresh":{"timedRefresh":0,"timeoutRefreshOnceOnly":false,"fiftyPercentAdRefresh":true}},"ab":[]}; console.log('✅ Libra is loaded!'); window.MMads = window.MMads || {}; MMads.adConfigAPI = MMads.adConfigAPI || {}; // prebidConfig window.MMads = window.MMads || {}; MMads.auctionFloors = MMads.auctionFloors || {}; window.MMads.auctionFloors.setFloorConfig({"billboard2":{"id":"1552493e0f0844c9aa10ef73ad78a9e4","floor":"5"},"other":{"id":"ade0de584a2a422f99e934cd54b87d52","floor":"50"},"billboard6":{"id":"d9f82edf28e44244a1bb7117f42ac476","floor":"5"},"billboard5":{"id":"b340b93231954f2689e7025e2c0b4d18","floor":"5"},"billboard4":{"id":"7ad9ab485fa5443fa94ccc9bdca0a54c","floor":"5"},"billboard3":{"id":"f3f09dd3fe0147ca8227ab5458eebddb","floor":"5"},"billboard9":{"id":"488a3fee6fac46538f5e3ae6e51fe20e","floor":"5"},"billboard8":{"id":"f026d0eec2024513afe5b28e3319ac0f","floor":"5"},"billboardfooter2":{"id":"311073fb68e74727993cb054fe4430ac","floor":"50"},"broadmatch":{"id":"1bf596551eb9405a8d491ce078883cd4","floor":"5"},"billboard7":{"id":"8c88c6ba9f90426e800eff9dd8d0da96","floor":"5"},"leaderboardac":{"id":"1d2472433a85494c9501b140d9a1ad07","floor":"5"},"leaderboard-fixed":{"id":"449b24392f4b4c3a8285e203a64b2e6b","floor":"50"},"billboardfooter":{"id":"bd907afd733c48f185f70915ac74154a","floor":"20"},"leaderboardfooter2":{"id":"b4e76d3c1cf74c1ca3f12ec305e5d477","floor":"20"},"leaderboard-flex-1":{"id":"6330c0d82bd34adda20418fdc163d9a1","floor":"5"},"leaderboard-flex-2":{"id":"69272dabe35b4230a13938af298f75ff","floor":"5"},"square-flex-2":{"id":"c13704bf38e94252aa37db34edaddc9d","floor":"5"},"square-flex-1":{"id":"6fc33fe17f4747dfb36dfebf395636da","floor":"5"},"adhesive":{"id":"64de72640b214667bb8b9619b8b6a19d","floor":"25"},"square-fixed-4":{"id":"d52b7b6757414cb6a7d9885ff4c77b5d","floor":"5"},"square-fixed-3":{"id":"b57dc2458de54ebfac6f1f50477c6b45","floor":"5"},"square-fixed-2":{"id":"37febc1e4b1d446eab0c4fc4c075b0fd","floor":"5"},"leaderboard-fixed-1":{"id":"18efe8595dde4c02997da03ea354f7c0","floor":"5"},"square-fixed-1":{"id":"f35a56c653844a519beacc6324430144","floor":"5"},"square-fixed-8":{"id":"4854e3a5e1df46d6bfd2d35901766c07","floor":"5"},"mob-square-fixed-8":{"id":"f5dd53128a5f45f79b6c0e10ef184775","floor":"20"},"mob-square-flex-1":{"id":"21369d2b78ed46adb737cd0a1807ac5c","floor":"5"},"square-fixed-7":{"id":"e6ab8ef52f3d4e8b8ac868affa8e50d3","floor":"5"},"mob-square-fixed-9":{"id":"bb244a8f3dcd4ce9a6dc10f703ec49b3","floor":"50"},"square-fixed-6":{"id":"2aac544603f648878aa881568d11cc09","floor":"5"},"leaderboardfooter-flex-2":{"id":"7c365e41079a42aaa31927e67c8da8e0","floor":"5"},"leaderboard-fixed-5":{"id":"06053e86f93941bda0b0f63ff74c4a36","floor":"20"},"square-fixed-5":{"id":"51cfda109b8746e9beef6c4e88481ac7","floor":"5"},"leaderboardfooter-flex-1":{"id":"0b11b76e67e74a2ebd92efb163f4194b","floor":"5"},"leaderboard-fixed-6":{"id":"814d9f6ea0a04d429c95152f1c83c42a","floor":"20"},"billboard":{"id":"c27504ff7166457ea12d0f4358d106ed","floor":"5"},"mob-square-fixed-1":{"id":"fd801e654fa44f5bbd341c9d9053cfdf","floor":"5"},"mob-square-fixed-2":{"id":"3e78f020556a47ba8c8fb5871b44e7f3","floor":"5"},"leaderboard":{"id":"08c6a6a889904e2781ba965da042d811","floor":"80"},"inline":{"id":"3d5b9b5843474c8c828a468e59265d37","floor":"5"},"square-fixed":{"id":"bab3683523e2411e99eb6ab43b2474af","floor":"5"},"leaderboardfooter":{"id":"0f753592739c47d1b45d66d7c441209b","floor":"20"},"dynamic-inline":{"id":"1fcee3f5892e4e1f8fd090836c51ed8e","floor":"50"},"square-fixed-9":{"id":"c85a0c059c444f8da27205fb620c12e5","floor":"5"},"mob-adhesive-banner-fixed":{"id":"1ae057445ee0474780904de1986d2af8","floor":"5"},"billboard11":{"id":"ae958d6ef4c24b51844f346b2417e7d7","floor":"5"},"primary":{"id":"ee7cd89f77d449f09425cff055e3b796","floor":"5"}}); (function(){ const mantleDependencies = { } ; const pageTargeting = { customSeries: '' ,abtest: 'lcid1' ,tax0: 'tho' ,custom: '' ,sweepId: '' ,rid: 'nc8237af2ccd9450ba2ebac0e51a0fa9013' ,sid: 'nc8237af2ccd9450ba2ebac0e51a0fa9013' } ; const baseSlotTargeting = { gtemplate: 'category' ,leaid: '156569' ,revenueGroup: '' ,docId: '4122478' ,viewtype: 'home' ,type: 'homepage' ,t: '100' ,au: '156569' ,tier: 'L' ,jny: '0' ,leuid: '151378030080892' ,sbj: 'pidtho_root' ,id: '4122478' ,aid: '' ,jnyroot: '' } ; const adLazyOffset = {'mob-square-fixed-intro-1': 750}; pageTargeting.w = Mntl.utilities.getW(); const initialSlots = []; initialSlots.push({ config: { id: 'square-flex-1', sizes: [[300, 250],[300, 600]], type: 'square', rtb: true, timedRefresh: 0, waitForThirdParty: false }, targeting: Mntl.fnUtilities.deepExtend({}, { pos: 'atf', priority: 2 }) }); const testIds = Mntl.GPT.getTestIds(); pageTargeting.ab = testIds; pageTargeting.bts = testIds; Mntl.utilities.onLoad(function() { Mntl.utilities.loadExternalJS({ src: '//securepubads.g.doubleclick.net/tag/js/gpt.js', async: false }); }); const options = { domain: 'www.thoughtco.com', templateName: 'taxonomy', isMobile: false, isTablet: false, isDesktop: true, dfpId: '3865', publisherProvidedId: 'd097d6ae-4831-4134-afc8-c0e50bab327f', singleRequest: false, useLmdFormat: true, useOxygen: true, useInfiniteRightRail: true, loadAdsAboveViewport: false, waitForNextFramePaint: false, revenueGroupAllowList: '', lmdSiteCode: 'hlt', pageTargeting, baseSlotTargeting, adLazyOffset, geo: { isInEurope: false, isInUsa: false }, initialSlots, auctionFloors: {"billboard2":{"id":"1552493e0f0844c9aa10ef73ad78a9e4","floor":"5"},"other":{"id":"ade0de584a2a422f99e934cd54b87d52","floor":"50"},"billboard6":{"id":"d9f82edf28e44244a1bb7117f42ac476","floor":"5"},"billboard5":{"id":"b340b93231954f2689e7025e2c0b4d18","floor":"5"},"billboard4":{"id":"7ad9ab485fa5443fa94ccc9bdca0a54c","floor":"5"},"billboard3":{"id":"f3f09dd3fe0147ca8227ab5458eebddb","floor":"5"},"billboard9":{"id":"488a3fee6fac46538f5e3ae6e51fe20e","floor":"5"},"billboard8":{"id":"f026d0eec2024513afe5b28e3319ac0f","floor":"5"},"billboardfooter2":{"id":"311073fb68e74727993cb054fe4430ac","floor":"50"},"broadmatch":{"id":"1bf596551eb9405a8d491ce078883cd4","floor":"5"},"billboard7":{"id":"8c88c6ba9f90426e800eff9dd8d0da96","floor":"5"},"leaderboardac":{"id":"1d2472433a85494c9501b140d9a1ad07","floor":"5"},"leaderboard-fixed":{"id":"449b24392f4b4c3a8285e203a64b2e6b","floor":"50"},"billboardfooter":{"id":"bd907afd733c48f185f70915ac74154a","floor":"20"},"leaderboardfooter2":{"id":"b4e76d3c1cf74c1ca3f12ec305e5d477","floor":"20"},"leaderboard-flex-1":{"id":"6330c0d82bd34adda20418fdc163d9a1","floor":"5"},"leaderboard-flex-2":{"id":"69272dabe35b4230a13938af298f75ff","floor":"5"},"square-flex-2":{"id":"c13704bf38e94252aa37db34edaddc9d","floor":"5"},"square-flex-1":{"id":"6fc33fe17f4747dfb36dfebf395636da","floor":"5"},"adhesive":{"id":"64de72640b214667bb8b9619b8b6a19d","floor":"25"},"square-fixed-4":{"id":"d52b7b6757414cb6a7d9885ff4c77b5d","floor":"5"},"square-fixed-3":{"id":"b57dc2458de54ebfac6f1f50477c6b45","floor":"5"},"square-fixed-2":{"id":"37febc1e4b1d446eab0c4fc4c075b0fd","floor":"5"},"leaderboard-fixed-1":{"id":"18efe8595dde4c02997da03ea354f7c0","floor":"5"},"square-fixed-1":{"id":"f35a56c653844a519beacc6324430144","floor":"5"},"square-fixed-8":{"id":"4854e3a5e1df46d6bfd2d35901766c07","floor":"5"},"mob-square-fixed-8":{"id":"f5dd53128a5f45f79b6c0e10ef184775","floor":"20"},"mob-square-flex-1":{"id":"21369d2b78ed46adb737cd0a1807ac5c","floor":"5"},"square-fixed-7":{"id":"e6ab8ef52f3d4e8b8ac868affa8e50d3","floor":"5"},"mob-square-fixed-9":{"id":"bb244a8f3dcd4ce9a6dc10f703ec49b3","floor":"50"},"square-fixed-6":{"id":"2aac544603f648878aa881568d11cc09","floor":"5"},"leaderboardfooter-flex-2":{"id":"7c365e41079a42aaa31927e67c8da8e0","floor":"5"},"leaderboard-fixed-5":{"id":"06053e86f93941bda0b0f63ff74c4a36","floor":"20"},"square-fixed-5":{"id":"51cfda109b8746e9beef6c4e88481ac7","floor":"5"},"leaderboardfooter-flex-1":{"id":"0b11b76e67e74a2ebd92efb163f4194b","floor":"5"},"leaderboard-fixed-6":{"id":"814d9f6ea0a04d429c95152f1c83c42a","floor":"20"},"billboard":{"id":"c27504ff7166457ea12d0f4358d106ed","floor":"5"},"mob-square-fixed-1":{"id":"fd801e654fa44f5bbd341c9d9053cfdf","floor":"5"},"mob-square-fixed-2":{"id":"3e78f020556a47ba8c8fb5871b44e7f3","floor":"5"},"leaderboard":{"id":"08c6a6a889904e2781ba965da042d811","floor":"80"},"inline":{"id":"3d5b9b5843474c8c828a468e59265d37","floor":"5"},"square-fixed":{"id":"bab3683523e2411e99eb6ab43b2474af","floor":"5"},"leaderboardfooter":{"id":"0f753592739c47d1b45d66d7c441209b","floor":"20"},"dynamic-inline":{"id":"1fcee3f5892e4e1f8fd090836c51ed8e","floor":"50"},"square-fixed-9":{"id":"c85a0c059c444f8da27205fb620c12e5","floor":"5"},"mob-adhesive-banner-fixed":{"id":"1ae057445ee0474780904de1986d2af8","floor":"5"},"billboard11":{"id":"ae958d6ef4c24b51844f346b2417e7d7","floor":"5"},"primary":{"id":"ee7cd89f77d449f09425cff055e3b796","floor":"5"}}, utils: { generateSlotId: Ref.GPT.generateSlotId, buildGptUrl: Ref.GPT.buildGptUrl }, displayOnScroll: false, displayOnConsent: true, adsToCollapse: ['leaderboard*','square*'], refreshConfig: { 'defaultConfig': { timedRefresh: 0, userClickRefreshSelector: "", timeoutRefreshOnceOnly: false, fiftyPercentAdRefresh: true, sizeOverrides: null } } }; if (Mntl.AdMetrics) { Mntl.AdMetrics.init("4122478", "nc8237af2ccd9450ba2ebac0e51a0fa9013", initialSlots.map(slot => slot.config.id), Date.now(), "0.1"); } else { Mntl.AdMetrics = { pushMetrics: () => {} }; } Mntl.GPT.setMantleDependencies(mantleDependencies); Mntl.GPT.init(options); }());window.dataLayer = window.dataLayer || []; // moved from gtm.ftl so we can initialize GTM only onLoad. From https://support.google.com/tagmanager/answer/6103696?hl=en Mntl.utilities.onLoad(function() { (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;defer=true;j.src='//www.googletagmanager.com/gtm.js?id='+i+dl;j.type="text/javascript";f.parentNode.insertBefore(j,f)})(window,document,'script','dataLayer','GTM-5P3SZGS'); }); window.dataLayer.push({ event: 'ab-proctor', 'abTests-proctor': { "99-0" : "useOxygen | useOxygen | use the Oxygenated ad unit format and slot names | 1" , "99-1" : "vanillaJSLazyAdRecipeSC | active | vanillaLazyAd.js enabled | 1" , "99-2" : "useFloorSearch | active | Use Floor Search | 1" , "99-3" : "continuousScrollMobSquareFlexOffset | active | Adds offset to mob-square-fixed-1 ad on CS articles | 1" , "99-4" : "recipescDesktopAdRefresh | active | active, right rail ads timed refresh active | 1" , "99-5" : "gamVideoUsePlcmt | active | Pass plcmt | 1" , "99-6" : "liveIntentConnectedIdTest | control | LiveIntent ConnectedID is enabled | 0" , "99-7" : "prebidConfigApi | active | Ad Config API is enabled | 1" , "99-8" : "prebidTotalTimeoutBudget | default | default | 1" , "99-9" : "useDynamicVideoSizes | active | active | 1" , "99-10" : "orion | active | Active | 1" , "99-11" : "rtbLibraryLoadTimeout | default | default | 1" , "99-12" : "prebidVideoUsePlcmt | active | Pass plcmt | 1" , "99-13" : "useLiveIntentSignedInUser | active | active | 1" , "99-14" : "removeAdTiers | active | active | 1" , "99-15" : "useLiveRamp | active | active | 1" , "99-16" : "amazonTamBidResponseTimeout | default | default | 1" , "78" : "fetchPriority | active | active | 1" , "99-18" : "prebidMetricTracker | active | Active | 1" } }); window.dataLayer.push({ envData: { environment: { environment: "k8s-prod", application: "reference", dataCenter: "us-west-1" }, server: { version: "5.14.0", title: "reference-launcher" }, client : { browserUA: navigator.userAgent, serverUA: "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 3.0.04506; .NET CLR 3.5.21022; .NET CLR 1.0.3705; .NET CLR 1.1.4322)", deviceType: "pc", usStateCode: "" }, mantle: "4.1.104" } }); (function(fnUtils, CMP) { const deferLoadTime = 5000; const readyForThirdPartyTrackingEvent = new CustomEvent('readyForThirdPartyTracking', { bubbles: true }); const readyForThirdPartyTracking = fnUtils.once(function() { window.dataLayer.push({event: 'readyForThirdPartyTracking'}); window.dispatchEvent(readyForThirdPartyTrackingEvent); }); const readyForDeferredScriptsEvent = new CustomEvent('readyForDeferredScripts', { bubbles: true }); const readyForDeferredScripts = fnUtils.once(function() { window.dataLayer.push({event: 'readyForDeferredScripts'}); window.dispatchEvent(readyForDeferredScriptsEvent); }); const hasTargetingConsentHandler = function() { const hasConsent = CMP.hasTargetingConsent(); if (hasConsent) { readyForThirdPartyTracking(); } // Trigger the readyForDeferredScripts if consent is given // or if the user has closed the banner(AlertBox) which exists for EU // or if the user optin consent is not required, which applies for non gdpr locations if (hasConsent || CMP.isAlertBoxClosed() || !CMP.isOptInConsent()) { readyForDeferredScripts(); } return hasConsent; }; const purposeOneConsentHandler = async function() { const hasPurposeOneConsent = await CMP.hasPurposeOneConsent(); if (hasPurposeOneConsent) { readyForThirdPartyTracking(); } if (hasPurposeOneConsent || CMP.isAlertBoxClosed()) { readyForDeferredScripts(); } return hasPurposeOneConsent; }; const onRequiredDomEvent = fnUtils.once(function() { if (!CMP) { readyForThirdPartyTracking(); readyForDeferredScripts(); return; } const handler = CMP.supportsTCData() ? purposeOneConsentHandler : hasTargetingConsentHandler; if (!CMP.isLoading()) { handler(); } CMP.onConsentChange(handler); }); [ ['adRendered', onRequiredDomEvent], ['beforeunload', onRequiredDomEvent], ['load', function() { setTimeout(onRequiredDomEvent, deferLoadTime); }] ].forEach(function(event) { window.addEventListener(event[0], event[1], { once: true }); }); })(Mntl.fnUtilities || {}, Mntl.CMP);window.dataLayer = window.dataLayer || []; (function() { var isContinuousScroll = document.querySelector('.mntl-continuous-scroll'); var pageViewDataAsJSON = {"primaryTaxonomyIds":"4122478","mantleVersion":"4.1.104","primaryTaxonomyNames":"ThoughtCo","fullUrl":"https://www.thoughtco.com/" + location.hash,"experienceType":"single page","entryType":"direct","excludeFromComscore":false,"internalSessionId":"nc8237af2ccd9450ba2ebac0e51a0fa9013","internalRequestId":"nc8237af2ccd9450ba2ebac0e51a0fa9013","hid":"","experienceTypeName":"","recircDocIdsFooter":"","euTrafficFlag":false,"isGoogleBot":false,"country":"SG","description":"From chemistry to computer programming, arts to World War II, ThoughtCo.com provides guides, tips, and resources to help you understand more about the world around us.","title":"ThoughtCo.com is the World's Largest Education Resource" || document.title || '',"authorId":"156569","viewType":"HOME","documentId":4122478,"revenueGroup":"","contentGroup":"Other","authorNames":"Staff Author","templateName":"TAXONOMY","templateId":"100","muid":"d097d6ae-4831-4134-afc8-c0e50bab327f","lastEditingAuthorId":"156569","lastEditingUserId":"151378030080892"}; var scrolledPageData = {}; var scrolledDocOrdinal; var scrolledPage; pageViewDataAsJSON.breakpointName = Ref.utilities.getW(); pageViewDataAsJSON.bounceExchangeId = 2473; if (isContinuousScroll) { pageViewDataAsJSON.experienceTypeName = 'continuous'; if (window.dataLayer && window.dataLayer.length) { //loop through events and collect previous scrolledDocOrdinal and scrolledPage values scrolledPageData = window.dataLayer.reduce( (acc, curr) => { if (curr.event == 'unifiedPageview') { acc.scrolledDocOrdinal = acc.scrolledDocOrdinal ? acc.scrolledDocOrdinal + 1 : 1; acc.scrolledPage = acc.scrolledPage ? acc.scrolledPage + " | " + (curr.documentId).toString() : (curr.documentId).toString(); } return acc; }, {}); } scrolledPage = scrolledPageData.scrolledPage ? scrolledPageData.scrolledPage + ' | ' + (pageViewDataAsJSON.documentId).toString() : (pageViewDataAsJSON.documentId).toString(); scrolledDocOrdinal = scrolledPageData.scrolledDocOrdinal ? scrolledPageData.scrolledDocOrdinal + 1 : 1; pageViewDataAsJSON.scrolledPage = scrolledPage; pageViewDataAsJSON.scrolledDocOrdinal = scrolledDocOrdinal; } Mntl.utilities.onLoad(function() { var isRecirc = false && document.querySelector('.mntl-recirc-section, .related-article-list, .masonry-list-section'); if (false && !isRecirc) { pageViewDataAsJSON.recircDocIdsFooter = ""; } Mntl.PageView.init(pageViewDataAsJSON); }); })();</script> <link rel="shortcut icon" href="/favicon.ico"> <link rel="icon" type="image/x-icon" href="/favicon.ico"> <link rel="apple-touch-icon-precomposed" sizes="57x57" href="/apple-touch-icon-57x57.png"> <link rel="apple-touch-icon-precomposed" sizes="60x60" href="/apple-touch-icon-60x60.png"> <link rel="apple-touch-icon-precomposed" sizes="76x76" href="/apple-touch-icon-76x76.png"> <link rel="apple-touch-icon-precomposed" sizes="120x120" href="/apple-touch-icon-120x120.png"> <link rel="apple-touch-icon-precomposed" sizes="152x152" href="/apple-touch-icon-152x152.png"> <link rel="apple-touch-icon-precomposed" sizes="180x180" href="/apple-touch-icon-180x180.png"> <meta name="msapplication-TileColor" content="#F4F4F4"/> <meta name="msapplication-TileImage" content="/static/5.14.0/icons/favicons/mstile-144x144.png"> <meta name="msapplication-square70x70logo" content="/static/5.14.0/icons/favicons/mstile-70x70.png"> <meta name="msapplication-square150x150logo" content="/static/5.14.0/icons/favicons/mstile-150x150.png"> <meta name="msapplication-square310x310logo" content="/static/5.14.0/icons/favicons/mstile-310x310.png"> <meta name="msapplication-wide310x150logo" content="/static/5.14.0/icons/favicons/mstile-310x150.png"> <div id="ie-notification-banner_1-0" class="comp ie-notification-banner mntl-block"><div id="ie-notification-banner__content_1-0" class="comp ie-notification-banner__content mntl-block" data-tracking-container="true"><svg class="icon icon-alert ie-notification-banner__icon-alert" > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-alert" href="#icon-alert"></use> </svg> <div id="ie-notification-banner__text-container_1-0" class="comp ie-notification-banner__text-container mntl-block"><span id="ie-notification-banner__text--bold_1-0" class="comp ie-notification-banner__text--bold mntl-text-block">Your web browser (Internet Explorer 7) is out of date. </span> <span id="ie-notification-banner__text_1-0" class="comp ie-notification-banner__text mntl-text-block">Update your browser for more security, speed, and the best experience on this site.</span></div> <a href="https://www.google.com/chrome" target="_blank" rel="noopener nocaes" class="ie-notification-banner__btn-update mntl-text-link ie-notification-banner__btn" id="ie-notification-banner__btn-update_1-0" data-tracking-container="true" ><span class="link__wrapper">Update Browser</span></a> <button id="ie-notification-banner__btn-close_1-0" class="comp ie-notification-banner__btn-close mntl-button ie-js-banner-dismiss ie-notification-banner__btn"> Ignore </button></div></div> <meta name="p:domain_verify" content="3e51479dbba3cc62a95e7ff4a368124e" /> <meta property="fb:pages" content="10913332166" /> <script type="application/ld+json"> { "@context": "http://schema.org", "@type": "WebPage", "mainEntityOfPage": { "@type": "Webpage", "@id": "https://www.thoughtco.com/" }, "headline": "ThoughtCo.com is the World's Largest Education Resource" ,"potentialAction": { "@type": "SearchAction", "target": "https://www.thoughtco.com/search?q={search_term_string}", "query-input": "required name=search_term_string'" } ,"publisher": { "@type": "Organization", "name": "ThoughtCo", "url": "https://www.thoughtco.com", "logo": { "@type": "ImageObject", "url": "https://www.thoughtco.com/thmb/ruwsr0VaZ-mxBD_vXVdKmhL0sjY=/250x60/filters:no_upscale():max_bytes(150000):strip_icc()/TC_schema_logo_250x60-59af144bd088c00010d45b5f.png", "width": 250, "height": 60 }, "brand": "ThoughtCo" , "publishingPrinciples": "https://www.thoughtco.com/about-us-4779650#toc-editorial-guidelines" , "sameAs" : [ "https://www.facebook.com/thoughtcodotcom", "https://www.flipboard.com/@thoughtco" ] , "address": { "@type": "PostalAddress", "streetAddress": "225 Liberty Street, 4th Floor", "addressLocality": "New York", "addressRegion": "NY", "postalCode": "10281", "addressCountry": "USA" } , "parentOrganization" : { "url": "https://www.dotdashmeredith.com", "brand": "Dotdash Meredith", "name": "Dotdash Meredith", "address": { "@type": "PostalAddress", "streetAddress": "225 Liberty Street, 4th Floor", "addressLocality": "New York", "addressRegion": "NY", "postalCode": "10281", "addressCountry": "USA" }, "logo": { "@type": "ImageObject", "url": "https://www.thoughtco.com/thmb/UrZUYJQsAwN-jGDeycKgTz1FKPg=/234x60/filters:no_upscale():max_bytes(150000):strip_icc()/dotdash-logo-e9cde67f713a45c68ce5def51d3ca409.jpg", "width": 234, "height": 60 }, "sameAs" : [ "https://en.wikipedia.org/wiki/Dotdash_Meredith", "https://www.instagram.com/dotdashmeredith/", "https://www.linkedin.com/company/dotdashmeredith/", "https://www.facebook.com/dotdashmeredith/" ] } } ,"description": "From chemistry to computer programming, arts to World War II, ThoughtCo.com provides guides, tips, and resources to help you understand more about the world around us." }</script> </head><body>  <svg class="mntl-svg-resource is-hidden"> <defs> <symbol id="icon-alert"> <svg width="30" height="29" fill="none" xmlns="http://www.w3.org/2000/svg"><path d="M13.2522 4.38081C14.077 2.92054 16.1389 2.92054 16.9637 4.38081L26.7065 21.6302C27.5313 23.0905 26.5003 24.9158 24.8507 24.9158H5.36517C3.7156 24.9158 2.68462 23.0905 3.5094 21.6302L13.2522 4.38081Z" fill="#fff"/><path fill-rule="evenodd" clip-rule="evenodd" d="M19.6063 2.76459L29.2795 20.1815C31.3267 23.8676 28.7677 28.4753 24.6732 28.4753H5.32681C1.23233 28.4753 -1.32671 23.8676 0.720529 20.1815L10.3937 2.76459C12.441 -0.921533 17.559 -0.921526 19.6063 2.76459ZM16.8425 4.42334C16.0236 2.94889 13.9764 2.94889 13.1575 4.42334L3.4843 21.8402C2.6654 23.3147 3.68902 25.1577 5.32681 25.1577H24.6732C26.311 25.1577 27.3346 23.3147 26.5157 21.8402L16.8425 4.42334Z" fill="#C00"/><path d="M13.8863 18.8426L12.8572 11.2V7.66641H17.1429V11.2L16.1279 18.8426H13.8863ZM13.0264 22.9992V20.1106H16.9878V22.9992H13.0264Z" fill="#222"/></svg> </symbol> <symbol id="icon-menu"> <svg viewBox="0 0 21 25" fill="none" xmlns="http://www.w3.org/2000/svg"><path d="M2 21.5C2 20.6716 2.67157 20 3.5 20H17.5C18.3284 20 19 20.6716 19 21.5C19 22.3284 18.3284 23 17.5 23H3.5C2.67157 23 2 22.3284 2 21.5Z" fill="#DCD8A0"/><path fill-rule="evenodd" clip-rule="evenodd" d="M3.5 18H17.5C19.433 18 21 19.567 21 21.5C21 23.433 19.433 25 17.5 25H3.5C1.567 25 0 23.433 0 21.5C0 19.567 1.567 18 3.5 18ZM3.5 20C2.67157 20 2 20.6716 2 21.5C2 22.3284 2.67157 23 3.5 23H17.5C18.3284 23 19 22.3284 19 21.5C19 20.6716 18.3284 20 17.5 20H3.5Z" fill="#333"/><path d="M2 12.5C2 11.6716 2.67157 11 3.5 11H17.5C18.3284 11 19 11.6716 19 12.5C19 13.3284 18.3284 14 17.5 14H3.5C2.67157 14 2 13.3284 2 12.5Z" fill="#DCD8A0"/><path fill-rule="evenodd" clip-rule="evenodd" d="M3.5 9H17.5C19.433 9 21 10.567 21 12.5C21 14.433 19.433 16 17.5 16H3.5C1.567 16 0 14.433 0 12.5C0 10.567 1.567 9 3.5 9ZM3.5 11C2.67157 11 2 11.6716 2 12.5C2 13.3284 2.67157 14 3.5 14H17.5C18.3284 14 19 13.3284 19 12.5C19 11.6716 18.3284 11 17.5 11H3.5Z" fill="#333"/><path d="M2 3.5C2 2.67157 2.67157 2 3.5 2H17.5C18.3284 2 19 2.67157 19 3.5C19 4.32843 18.3284 5 17.5 5H3.5C2.67157 5 2 4.32843 2 3.5Z" fill="#DCD8A0"/><path fill-rule="evenodd" clip-rule="evenodd" d="M3.5 0H17.5C19.433 0 21 1.567 21 3.5C21 5.433 19.433 7 17.5 7H3.5C1.567 7 0 5.433 0 3.5C0 1.567 1.567 0 3.5 0ZM3.5 2C2.67157 2 2 2.67157 2 3.5C2 4.32843 2.67157 5 3.5 5H17.5C18.3284 5 19 4.32843 19 3.5C19 2.67157 18.3284 2 17.5 2H3.5Z" fill="#333"/></svg> </symbol> <symbol id="icon-close"> <svg viewBox="0 0 21 21" fill="none" xmlns="http://www.w3.org/2000/svg"><path fill-rule="evenodd" clip-rule="evenodd" d="M2.43934 15.8744C1.85355 16.4602 1.85355 17.4099 2.43934 17.9957C3.02513 18.5815 3.97487 18.5815 4.56066 17.9957L10.2175 12.3388L15.8744 17.9957C16.4602 18.5815 17.4099 18.5815 17.9957 17.9957C18.5815 17.4099 18.5815 16.4602 17.9957 15.8744L12.3388 10.2175L17.9957 4.56066C18.5815 3.97487 18.5815 3.02513 17.9957 2.43934C17.4099 1.85355 16.4602 1.85355 15.8744 2.43934L10.2175 8.09619L4.56066 2.43934C3.97488 1.85355 3.02513 1.85355 2.43934 2.43934C1.85356 3.02513 1.85356 3.97487 2.43934 4.56066L8.0962 10.2175L2.43934 15.8744Z" fill="#DCD8A0"/><path fill-rule="evenodd" clip-rule="evenodd" d="M1.02513 14.4602L5.26777 10.2175L1.02513 5.97487C-0.341705 4.60804 -0.341705 2.39196 1.02513 1.02513C2.39196 -0.341708 4.60804 -0.341709 5.97488 1.02513L10.2175 5.26776L14.4602 1.02513C15.827 -0.341708 18.0431 -0.341708 19.4099 1.02513C20.7767 2.39196 20.7767 4.60804 19.4099 5.97487L15.1673 10.2175L19.4099 14.4602C20.7767 15.827 20.7767 18.0431 19.4099 19.4099C18.0431 20.7767 15.827 20.7767 14.4602 19.4099L10.2175 15.1673L5.97487 19.4099C4.60804 20.7767 2.39196 20.7767 1.02513 19.4099C-0.341709 18.0431 -0.341708 15.827 1.02513 14.4602ZM10.2175 12.3388L15.8744 17.9957C16.4602 18.5815 17.4099 18.5815 17.9957 17.9957C18.5815 17.4099 18.5815 16.4602 17.9957 15.8744L12.3388 10.2175L17.9957 4.56066C18.5815 3.97487 18.5815 3.02513 17.9957 2.43934C17.4099 1.85355 16.4602 1.85355 15.8744 2.43934L10.2175 8.09619L4.56066 2.43934C3.97488 1.85355 3.02513 1.85355 2.43934 2.43934C1.85356 3.02513 1.85356 3.97487 2.43934 4.56066L8.0962 10.2175L2.43934 15.8744C1.85355 16.4602 1.85355 17.4099 2.43934 17.9957C3.02513 18.5815 3.97487 18.5815 4.56066 17.9957L10.2175 12.3388Z" fill="#333"/></svg> </symbol> <symbol id="icon-logo"> <svg version="1.1" class="logo-img" xmlns="http://www.w3.org/2000/svg" x="0" y="0" viewBox="-169.7 -50 913.8 182.2" xml:space="preserve"><g class="logo-thought"><path d="M506.9 63.3c-1.7.4-5 1-8.7 1-6.1 0-8.1-1-10.6-3.9-2.1-2.5-2.1-6.6-2.1-12.4V12.6H507v-21h-12.1v0h-9.3v-25.8l-24.9-.1v25.9l-12 0 0 20.9h12v32.7c0 13.2 2.4 21.2 6.9 27.7 6.8 9.8 17.2 13.4 32.1 13.4 3.8 0 9.3-.8 12.5-1.9L506.9 63.3zM-73.1-49.6v23h-35.4v111h-25.8v-111h-35.4v-23H-73.1zM-35.5 84.4h-24.9V-50h24.9v48.2c6.9-5.4 15.7-8.6 25.3-8.6 12.8 0 24.5 5.7 32.1 14.9 6.1 7.3 9.6 16.6 9.6 32.5v47.3H6.6V35.2c0-9.2-2.1-14-5.6-17.4-3.3-3.3-8.2-5.2-14-5.2-10.5 0-19.1 6.7-22.6 11.5V84.4zM88.6-10.3c28.1 0 49.4 21.6 49.4 48.4 0 26.8-21.2 48.2-49.4 48.2S39.2 64.9 39.2 38.1C39.2 11.3 60.4-10.3 88.6-10.3zM88.6 63.3c14.5 0 24.5-11.3 24.5-25.3s-9.9-25.4-24.5-25.4c-14.5 0-24.5 11.5-24.5 25.4S74 63.3 88.6 63.3zM235.1-8.4v92.8h-23.9v-7.5c-7.3 6.5-16.1 9.4-25.1 9.4-12.8 0-24.3-5.9-31.6-14.9-5.9-7.3-9.4-16.8-9.4-30.6V-8.4h24.9v50.1c0 8.4 1.7 12.6 4.6 15.9 3.8 4.2 9.2 5.7 14 5.7 10.5 0 18.2-7.1 21.6-11.5V-8.4H235.1zM340.3 79.2c0 16.6-2.9 26.6-8.4 34.4-8.4 11.7-23.3 18.6-41.1 18.6-18.2 0-35.4-8.4-44.6-19.1l15.7-16.3c5 5.4 13.6 13.4 28.9 13.4 8 0 14.7-2.5 18.9-7.5 3.8-4.2 5.7-9.9 5.7-21.8v-3.1c-7.5 5.7-15.5 8.4-24.9 8.4-13.8 0-27-6.1-35.2-15.7-7.3-8.4-11.7-19.9-11.7-32.5 0-27.4 20.3-48.4 45.5-48.4 10.5 0 19.9 3.4 27.2 9.4v-7.5h23.9V79.2zM315.4 24.1c-5.2-6.9-13.4-11.5-23-11.5-14.5 0-23.9 12.1-23.9 25.4 0 14.5 10.5 25.3 24.5 25.3 9.4 0 17.6-4.6 22.4-11.5V24.1zM378.3 84.4h-24.9V-50h24.9v48.2c6.9-5.4 15.7-8.6 25.3-8.6 12.8 0 24.5 5.7 32.1 14.9 6.1 7.3 9.6 16.6 9.6 32.5v47.3h-24.9V35.2c0-9.2-2.1-14-5.6-17.4-3.3-3.3-8.2-5.2-14-5.2-10.5 0-19.1 6.7-22.6 11.5V84.4z"/><g class="logo-co" fill="#BEAB72"><path d="M590 67c-25.8 0-45.7-19.9-45.7-45.9 0-25.4 19.1-45.9 44.6-45.9 13.2 0 24.5 5.7 32.5 13.8l16.6-17.6c-12.1-11.7-29.1-19.1-49-19.1-41.7 0-70.6 30.4-70.6 68.9s29.3 68.9 71 68.9c15 0 28.3-4 39.1-10.5-5-6.2-8.4-13.6-10-21.8C611.2 63.3 601.7 67 590 67zM742.2 67.5c-1.2-2.1-2.9-3.8-5.1-5-2.2-1.2-4.5-1.8-6.9-1.8-3.4 0-6.4 1.2-9 3.5-3 2.7-4.5 6.1-4.5 10.2 0 3.8 1.3 7 4 9.7 2.6 2.7 5.8 4 9.6 4 2.5 0 4.9-.6 7-1.8 2.1-1.2 3.8-2.9 5-5 1.2-2.1 1.8-4.4 1.8-6.9C744 71.8 743.4 69.6 742.2 67.5z"/><path d="M669.8,5.1c-24.7,0-43.3,19-43.3,42.5c0,1.2,0.1,2.4,0.2,3.6c0.7,9,4.2,17.1,9.7,23.6c7.8,9.3,19.7,15.1,33.5,15.1 c24.7,0,43.3-18.8,43.3-42.3C713.1,24.1,694.4,5.1,669.8,5.1z M670.3,70.4c-7.1,0-13.1-3-16.9-8c-3.2-3.9-5.1-9-5.1-14.7 c0-12.3,8.7-22.3,21.5-22.3c6.5,0,11.9,2.6,15.7,6.7c3.9,4,6.3,9.7,6.3,16.1C691.7,61,682.7,70.4,670.3,70.4z"/></g></g></svg> </symbol> <symbol id="icon-search"> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 29 34"><path d="M5.04807 30.5496C6.15292 31.1875 7.5657 30.8089 8.20358 29.7041L13.6111 20.338C14.249 19.2332 13.8704 17.8204 12.7656 17.1825L12.7179 17.155C11.6131 16.5171 10.2003 16.8957 9.56242 18.0005L4.15492 27.3666C3.51703 28.4714 3.89558 29.8842 5.00043 30.5221L5.04807 30.5496Z" fill="#DCD8A0" stroke="#333" stroke-width="2"/><path d="M9.88244 22.8385C5.33866 20.2151 3.78184 14.405 6.4052 9.86122C9.02855 5.31744 14.8387 3.76062 19.3824 6.38397C23.9262 9.00733 25.483 14.8174 22.8597 19.3612C20.2363 23.905 14.4262 25.4618 9.88244 22.8385Z" stroke="#333" stroke-width="2"/></svg> </symbol> <symbol id="icon-caret-down"> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 14 14"><path fill-rule="evenodd" clip-rule="evenodd" d="M7.77819 12.3744C7.1924 12.9602 6.24266 12.9602 5.65687 12.3744L1.44243e-05 6.71751L2.12133 4.59619L6.71753 9.19239L11.3137 4.59619L13.435 6.71751L7.77819 12.3744Z" fill="#DE2229"/></svg> </symbol> <symbol id="icon-facebook"> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 43.8 34"><path d="M22.4,30.1V18.9h3.7l0.6-4.4h-4.3v-2.8c0-1.3,0.3-2.1,2.2-2.1h2.3V5.8c-0.4-0.1-1.8-0.2-3.4-0.2c-3.3,0-5.6,2-5.6,5.7v3.2h-3.8v4.4h3.8v11.2L22.4,30.1L22.4,30.1z"/></svg> </symbol> <symbol id="icon-flipboard"> <svg xmlns="http://www.w3.org/2000/svg" viewBox="240.4 241 17.3 17.3"><path d="M252 241 246.2 241 240.4 241 240.4 246.7 240.4 252.5 240.4 258.3 246.2 258.3 246.2 252.6 251.9 252.6 251.9 246.8 257.7 246.8 257.7 241z"/><path d="M252 241 246.2 241 246.2 246.8 252 246.8 257.7 246.8 257.7 241zM246.2 246.8H252V252.60000000000002H246.2z"/></svg> </symbol> <symbol id="icon-instagram"> <svg xmlns="http://www.w3.org/2000/svg" x="0" y="0" viewBox="0 0 43.8 34" xml:space="preserve"><path d="M21.8,8.5c2.9,0,3.2,0,4.4,0.1c1.1,0,1.6,0.2,2,0.4c0.5,0.2,0.9,0.4,1.2,0.8c0.4,0.4,0.6,0.7,0.8,1.2c0.1,0.4,0.3,1,0.4,2c0.1,1.1,0.1,1.5,0.1,4.4s0,3.2-0.1,4.4c0,1.1-0.2,1.6-0.4,2c-0.2,0.5-0.4,0.9-0.8,1.2c-0.4,0.4-0.7,0.6-1.2,0.8c-0.4,0.1-1,0.3-2,0.4c-1.1,0.1-1.5,0.1-4.4,0.1s-3.2,0-4.4-0.1c-1.1,0-1.6-0.2-2-0.4c-0.5-0.2-0.9-0.4-1.2-0.8c-0.4-0.4-0.6-0.7-0.8-1.2c-0.1-0.4-0.3-1-0.4-2c-0.1-1.1-0.1-1.5-0.1-4.4s0-3.2,0.1-4.4c0-1.1,0.2-1.6,0.4-2c0.2-0.5,0.4-0.9,0.8-1.2c0.4-0.4,0.7-0.6,1.2-0.8c0.4-0.1,1-0.3,2-0.4C18.6,8.5,18.9,8.5,21.8,8.5 M21.8,6.6c-2.9,0-3.3,0-4.5,0.1c-1.2,0.1-1.9,0.2-2.6,0.5c-0.7,0.3-1.3,0.6-1.9,1.2c-0.6,0.6-1,1.2-1.2,1.9c-0.3,0.7-0.4,1.5-0.5,2.6C11,14.1,11,14.4,11,17.4c0,2.9,0,3.3,0.1,4.5c0.1,1.2,0.2,1.9,0.5,2.6c0.3,0.7,0.6,1.3,1.2,1.9c0.6,0.6,1.2,1,1.9,1.2c0.7,0.3,1.5,0.4,2.6,0.5c1.2,0.1,1.5,0.1,4.5,0.1s3.3,0,4.5-0.1c1.2-0.1,1.9-0.2,2.6-0.5c0.7-0.3,1.3-0.6,1.9-1.2c0.6-0.6,1-1.2,1.2-1.9c0.3-0.7,0.4-1.5,0.5-2.6c0.1-1.2,0.1-1.5,0.1-4.5s0-3.3-0.1-4.5c-0.1-1.2-0.2-1.9-0.5-2.6c-0.3-0.7-0.6-1.3-1.2-1.9c-0.6-0.6-1.2-1-1.9-1.2c-0.7-0.3-1.5-0.4-2.6-0.5C25.1,6.6,24.7,6.6,21.8,6.6L21.8,6.6z"/><path d="M21.8,11.8c-3.1,0-5.5,2.5-5.5,5.5s2.5,5.5,5.5,5.5s5.5-2.5,5.5-5.5S24.9,11.8,21.8,11.8zM21.8,21c-2,0-3.6-1.6-3.6-3.6s1.6-3.6,3.6-3.6s3.6,1.6,3.6,3.6S23.8,21,21.8,21z"/><circle cx="27.6" cy="11.6" r="1.3"/></svg> </symbol> <symbol id="icon-linkedin"> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 41.8 41.8"><path d="M12.2 18.2h3.9v12.7h-3.9V18.2zm1.9-6.3c1.3 0 2.3 1 2.3 2.3s-1 2.3-2.3 2.3-2.3-1-2.3-2.3c0-1.3 1.1-2.3 2.3-2.3M18.6 18.2h3.8v1.7h.1c.8-1.3 2.2-2.1 3.7-2 4 0 4.7 2.6 4.7 6v7H27v-6.2c0-1.5 0-3.4-2-3.4s-2.3 1.6-2.3 3.2v6.3h-3.9l-.2-12.6z"/></svg> </symbol> <symbol id="icon-pinterest"> <svg xmlns="http://www.w3.org/2000/svg" viewBox="-1217.8 0 640 480"><path d="M-888.5,96c-77.6,0-120,52.2-120,108.7c0,26.8,14.1,59.3,36.7,70.6c2.8,1.4,5.6,1.4,5.6-2.8c0-2.8,4.2-14.1,5.6-21.2c0-1.4,0-2.8-1.4-5.6c-7.1-8.5-14.1-25.4-14.1-40.9c0-39.5,29.6-79.1,81.9-79.1c43.8,0,74.8,29.6,74.8,73.4c0,49.4-24,83.3-56.5,83.3c-18.4,0-31.1-14.1-26.8-32.5c5.6-21.2,15.5-45.2,15.5-60.7c0-14.1-7.1-25.4-22.6-25.4c-18.4,0-32.5,18.4-32.5,43.8c0,15.5,5.6,26.8,5.6,26.8s-18.4,76.2-21.2,90.4c-5.6,24,1.4,62.1,1.4,66.4c0,1.4,2.8,2.8,2.8,1.4c1.4-2.8,24-35.3,29.6-57.9c2.8-8.5,11.3-42.4,11.3-42.4c5.6,11.3,22.6,21.2,40.9,21.2c55.1,0,93.2-50.8,93.2-112.9C-776.9,141.2-824.9,96-888.5,96z"/></svg> </symbol> <symbol id="icon-x"> <svg viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><path d="M13.6468 10.4686L20.9321 2H19.2057L12.8799 9.3532L7.82741 2H2L9.6403 13.1193L2 22H3.72649L10.4068 14.2348L15.7425 22H21.57L13.6468 10.4686ZM11.2821 13.2173L10.508 12.1101L4.34857 3.29968H7.00037L11.9711 10.4099L12.7452 11.5172L19.2066 20.7594H16.5548L11.2821 13.2173Z"/></svg> </symbol> <symbol id="icon-privacy-options"> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 30 14"><path fill="#FFF" d="M7.4 12.8h6.8l3.1-11.6H7.4C4.2 1.2 1.6 3.8 1.6 7s2.6 5.8 5.8 5.8z"/><path fill="#06f" d="M22.6 0H7.4c-3.9 0-7 3.1-7 7s3.1 7 7 7h15.2c3.9 0 7-3.1 7-7s-3.2-7-7-7zm-21 7c0-3.2 2.6-5.8 5.8-5.8h9.9l-3.1 11.6H7.4c-3.2 0-5.8-2.6-5.8-5.8z"/><path fill="#FFF" d="M24.6 4c.2.2.2.6 0 .8L22.5 7l2.2 2.2c.2.2.2.6 0 .8-.2.2-.6.2-.8 0l-2.2-2.2-2.2 2.2c-.2.2-.6.2-.8 0-.2-.2-.2-.6 0-.8L20.8 7l-2.2-2.2c-.2-.2-.2-.6 0-.8.2-.2.6-.2.8 0l2.2 2.2L23.8 4c.2-.2.6-.2.8 0z"/><path fill="#06f" d="M12.7 4.1c.2.2.3.6.1.8L8.6 9.8c-.1.1-.2.2-.3.2-.2.1-.5.1-.7-.1L5.4 7.7c-.2-.2-.2-.6 0-.8.2-.2.6-.2.8 0L8 8.6l3.8-4.5c.2-.2.6-.2.9 0z"/></svg> </symbol> <symbol id="mntl-dotdash-universal-nav__logo"> <svg xmlns="http://www.w3.org/2000/svg" viewBox="5 2.8 290 69"><circle cx="39.6" cy="37.4" r="34.3" fill="#f44b34"/><path fill="#fff" d="M50.4 17.9c-1.7-1.8-4-2.6-7-2.6-9.1-.1-12.4-.1-13.2-.1L27.3 22h8.1L30 28v21h-.1l.1.1v6.7l-3.6 4h18.5L53 51V25c0-.1.1-4.3-2.6-7.1zm-5.2 19.6-7.4 7.8V41l7.4-7.8v4.3zm-7.4-15.4h3c.9 0 2.1-.1 3.1.9s1.4 2.5 1.4 4.9v3.6l-7.4 7.8-.1-17.2zm-4.9 30.1 3.3-3.6 9-9.5v13.1c0 .1-12.3.1-12.3 0z"/><path fill="#009ad9" d="m99.645 22.637 6.505-6.506 4.172 4.172-6.505 6.506zM121 44l4.2 4.2 6.5-6.5-4.2-4.2zm-3.2-31.2c1.8-1.8 4.7-1.8 6.5 0 1.9 1.9 1.7 4.8 0 6.5l-3.3 3.3 4.2 4.2 3.3-3.3c2-2 4.9-1.6 6.5 0 2 2 1.6 4.9 0 6.5l-3.3 3.3 4.2 4.2 3.3-3.3c4.2-4.2 4-10.8 0-14.8-2.8-2.8-6.1-3.1-7.6-3.1.1-1.5-.3-4.8-3.1-7.6-3.9-3.9-10.6-4.2-14.8 0l-3.3 3.3 4.2 4.2 3.2-3.4zm-7.5 20.6 4.2 4.1L121 31l-4.2-4.1-6.5 6.5z"/><path fill="#6ebd44" d="m99.6 52.4 6.6 6.5 4.1-4.2-6.5-6.5zm36.3-14.9-4.2 4.2L135 45c1.6 1.6 2 4.5 0 6.5-1.6 1.6-4.5 2.1-6.5 0l-3.3-3.3-4.2 4.2 3.3 3.3c1.7 1.7 1.9 4.6 0 6.5-1.8 1.8-4.7 1.8-6.5 0l-3.3-3.3-4.2 4.2 3.3 3.3c4.2 4.2 10.9 3.9 14.8 0 2.8-2.8 3.1-6.1 3.1-7.6 1.5 0 4.8-.3 7.6-3.1 4-4 4.2-10.6 0-14.8l-3.2-3.4zm-25.6 4.2 6.5 6.5L121 44l-6.5-6.5zm14.9-14.8L121 31l6.5 6.5 4.2-4.1-6.5-6.5z"/><path fill="#f68f1e" d="m110.332 54.607 6.506-6.506 4.172 4.172-6.506 6.505zM102.8 62.2c-1.6 1.6-4.5 2-6.5 0-1.6-1.6-2.1-4.5 0-6.5l3.3-3.3-4.2-4.2-3.3 3.3c-1.7 1.7-4.6 1.9-6.5 0-1.8-1.8-1.8-4.7 0-6.5l3.3-3.3-4.2-4.2-3.3 3.3c-4.2 4.2-3.9 10.9 0 14.8 2.8 2.8 6.1 3.1 7.6 3.1 0 1.5.3 4.8 3.1 7.6 4 4 10.6 4.2 14.8 0l3.3-3.3-4.2-4.2-3.2 3.4zm3.4-24.7L99.6 44l4.2 4.2 6.5-6.5zM95.5 26.9 89 33.4l4.1 4.1 6.5-6.5z"/><path fill="#ec174c" d="m99.6 44-6.5-6.5-4.1 4.2 6.5 6.5zm-14-14c-1.8-1.8-1.8-4.7 0-6.5 1.9-1.9 4.8-1.7 6.5 0l3.3 3.3 4.2-4.2-3.3-3.3c-2-2-1.6-4.9 0-6.5 2-2 4.9-1.6 6.5 0l3.3 3.3 4.2-4.2-3.3-3.2c-4.2-4.2-10.8-4-14.8 0-2.8 2.8-3.1 6.1-3.1 7.6-1.5-.1-4.9.3-7.6 3.1-3.9 3.9-4.2 10.6 0 14.8l3.3 3.3 4.2-4.2-3.4-3.3zm24.73-9.682 4.172-4.172 6.505 6.505-4.172 4.172zM106.2 37.5l4.1-4.1-6.5-6.5-4.2 4.1 6.6 6.5z"/><path fill="#573357" d="m106.142 16.042 4.171-4.172 4.172 4.172-4.171 4.172z"/><path fill="#be272d" d="m84.81 37.543 4.172-4.172 4.172 4.172-4.172 4.172z"/><path fill="#008e4c" d="m127.497 37.555 4.171-4.172 4.172 4.172-4.171 4.172z"/><path fill="#7a773e" d="m106.172 58.866 4.172-4.172 4.172 4.172-4.172 4.172z"/><path fill="#443639" d="m116.856 26.74 4.172-4.172 4.172 4.172-4.172 4.172z"/><path fill="#803136" d="m95.455 48.169 4.172-4.172 4.172 4.172-4.172 4.172z"/><path fill="#593438" d="m95.446 26.753 4.172-4.172 4.172 4.173-4.172 4.171z"/><path fill="#443639" d="m106.155 37.456 4.172-4.172 4.172 4.171-4.172 4.172z"/><path fill="#2a6442" d="m116.871 48.153 4.172-4.172 4.172 4.172-4.172 4.172z"/><path d="M170.4 13.5c-2.5-2.2-5.7-3.3-9.6-3.3h-7.2v23.6h7.6c3.8 0 7-1.1 9.4-3.3s3.6-5 3.6-8.5-1.3-6.3-3.8-8.5zm.1 8.5c0 2.6-.9 4.7-2.6 6.2-1.7 1.6-4.1 2.3-7 2.3h-3.8V13.4h3.8c2.9 0 5.2.8 7 2.3 1.7 1.5 2.6 3.7 2.6 6.3zm14.6-6.3c-2.5 0-4.7.9-6.4 2.7s-2.6 4-2.6 6.6.9 4.8 2.6 6.6c1.7 1.8 3.9 2.7 6.4 2.7h.1v-.1c2.5 0 4.7-.9 6.4-2.7s2.6-4 2.6-6.6c0-2.5-.9-4.8-2.6-6.6-1.8-1.7-3.9-2.6-6.5-2.6zm4.1 13.7c-.5.6-1.1 1-1.8 1.3s-1.4.3-2.2.3c-1.7 0-3-.6-4.1-1.8-1.1-1.2-1.6-2.7-1.6-4.4 0-1.7.6-3.2 1.6-4.3 1.1-1.2 2.4-1.7 4.1-1.7 1.6 0 3 .6 4 1.7 1.1 1.2 1.6 2.6 1.6 4.3 0 1.9-.5 3.4-1.6 4.6zm16.9.8c-.5.6-1.3.9-2.3.9-1.6 0-2.4-.9-2.4-2.7v-9.2h5v-3h-5v-4.4h-3.3v4.4h-2.9l.1 3h2.9v9.3c0 1.9.5 3.3 1.4 4.3s2.2 1.5 3.9 1.5c1.8 0 3.2-.5 4.2-1.5l-1.6-2.6zm38.1-11.6c-1.5-2-3.5-3-6.1-3-2.5 0-4.5.9-6.1 2.7-1.6 1.8-2.4 4-2.4 6.6 0 2.7.8 4.9 2.5 6.6 1.7 1.8 3.7 2.7 6.1 2.7 2.6 0 4.6-1 6.1-3.1v2.6h3.4V16.1h-3.4v2.5h-.1zm-1.6 2c1.1 1.2 1.6 2.6 1.6 4.3s-.5 3.2-1.6 4.4c-.5.6-1.1 1-1.8 1.3s-1.4.4-2.2.4c-1.7 0-3-.6-4.1-1.8-1.1-1.2-1.6-2.7-1.6-4.4 0-1.7.6-3.2 1.6-4.3 1.1-1.2 2.4-1.7 4.1-1.7 1.6.1 2.9.6 4 1.8zm17.9 3.6c-.9-.3-1.9-.6-3-.9-1-.3-1.9-.6-2.5-1-.7-.4-1-1-1-1.6l.1-.1c0-.7.3-1.2.9-1.6.6-.4 1.4-.6 2.3-.6 2 0 3.4.7 4.5 2l2-2c-1.3-1.8-3.5-2.7-6.6-2.7-1.9 0-3.5.5-4.7 1.4-1.2 1-1.7 2.1-1.7 3.5 0 1.2.3 2.1 1 2.9s1.5 1.3 2.6 1.7c1.1.4 2 .7 2.9 1 1 .3 1.8.7 2.4 1.1.7.5 1 1 1 1.8s-.3 1.4-.9 1.8c-.6.5-1.4.7-2.5.7-2.3 0-4.1-.8-5.3-2.3l-2 2.2c1.5 1.9 3.9 2.9 7.1 2.9 2.2 0 3.9-.5 5.1-1.5s1.8-2.3 1.8-3.8c0-1.2-.3-2.2-1-3-.6-.9-1.5-1.4-2.5-1.9zm14.9-8.6c-2.3 0-4.1.8-5.2 2.5V8.4h-3.4v25.4h3.4l.1-10.3c0-1.4.4-2.6 1.2-3.4.8-.8 1.8-1.2 3.2-1.2 1.3 0 2.4.4 3.2 1.3.8.8 1.2 2 1.2 3.4v10.3h3.4V23c0-2.3-.6-4-1.9-5.4-1.4-1.4-3.1-2-5.2-2zm-52.2 3c-1.5-2-3.5-3-6.1-3-2.5 0-4.5.9-6.1 2.7-1.6 1.8-2.4 4-2.4 6.6 0 2.7.8 4.9 2.5 6.6 1.7 1.8 3.7 2.7 6.1 2.7 2.6 0 4.6-1 6.1-3.1v2.6h3.4V8.4h-3.4v10.2h-.1zm-1.6 2c1.1 1.2 1.6 2.6 1.6 4.3s-.5 3.2-1.6 4.4c-1.1 1.2-2.4 1.8-4 1.8-1.7 0-3-.6-4.1-1.8-1.1-1.2-1.6-2.7-1.6-4.4 0-1.7.6-3.2 1.6-4.3 1.1-1.2 2.4-1.7 4.1-1.7 1.6 0 2.9.5 4 1.7zm48.8 19.9h-3.6v19.1c0 2.4.7 4.1 2.1 5.1 1.2.9 3.1 1.4 5.6 1.4h.1v-3h-.1c-1.2 0-2.1-.2-2.7-.6-.9-.6-1.4-1.7-1.4-3.3V51h4.1v-3h-4.1v-7.5zm-96.2 7c-1.4 0-2.6.3-3.7 1-1 .6-1.7 1.5-2.3 2.6-1.2-2.4-3.2-3.6-6-3.6-2.2 0-4 .9-5.2 2.6V48h-3.5v18.2h3.5l.2-10.7c0-1.5.4-2.6 1.1-3.5.7-.9 1.8-1.3 3.1-1.3s2.3.4 3.1 1.3c.8.9 1.2 2 1.2 3.5v10.6h3.4V55.5c0-1.5.4-2.6 1.2-3.5s1.8-1.3 3.2-1.3c1.3 0 2.3.4 3.1 1.3.7.9 1.1 2 1.1 3.5v10.6h3.5V55c0-2.3-.6-4.1-1.9-5.5-1.3-1.3-3-2-5.1-2zm18.9 0c-2.5 0-4.7.9-6.4 2.8-1.7 1.9-2.6 4.1-2.6 6.8s.9 5 2.7 6.8c1.8 1.8 4.1 2.8 6.8 2.8h.1v-.1c1.4 0 2.7-.3 3.9-.7 1.2-.5 2.2-1.1 3-1.9l-1.8-2.4c-1.3 1.3-3 2-5 2-1.7 0-3.1-.5-4.2-1.6-1.1-1-1.8-2.4-2-4h14.3c.1-.3.1-.7.1-1.2 0-2.5-.9-4.7-2.6-6.5-1.6-1.8-3.8-2.8-6.3-2.8zm.1 3c1.4 0 2.6.5 3.6 1.3 1 .9 1.6 2.1 1.8 3.8h-10.8c.3-1.5.9-2.7 1.8-3.7 1-.9 2.2-1.4 3.6-1.4zm22.5-2.3c-.6-.5-1.6-.8-2.8-.8-1.9 0-3.4.9-4.5 2.6v-2H205v18.2h3.5l-.1-10.5c0-1.5.3-2.7.9-3.6.6-.9 1.5-1.3 2.6-1.3.9 0 1.7.2 2.3.7h.1l1.4-3.3zm9-.7c-2.5 0-4.7.9-6.4 2.8-1.7 1.9-2.6 4.1-2.6 6.8s.9 5 2.7 6.8c1.8 1.8 4.1 2.8 6.8 2.8h.1v-.1c1.4 0 2.7-.3 3.9-.7 1.2-.5 2.2-1.1 3-1.9l-1.8-2.4c-1.3 1.3-3 2-5 2-1.7 0-3.1-.5-4.2-1.6-1.1-1-1.8-2.4-2-4h14.3c.1-.3.1-.7.1-1.2 0-2.5-.9-4.7-2.6-6.5-1.6-1.8-3.8-2.8-6.3-2.8zm.1 3c1.4 0 2.6.5 3.6 1.3 1 .9 1.6 2.1 1.8 3.8h-10.8c.3-1.5.9-2.7 1.8-3.7.9-.9 2.1-1.4 3.6-1.4zm26.1 0c-1.5-2-3.6-3.1-6.3-3.1-2.5 0-4.6.9-6.3 2.7s-2.5 4.1-2.5 6.8.9 5 2.5 6.8c1.7 1.8 3.8 2.7 6.3 2.7 2.6 0 4.7-1.1 6.3-3.2v2.7h3.5V40.5h-3.5v10zm-1.7 2c1.1 1.2 1.6 2.7 1.6 4.5 0 1.7-.6 3.3-1.6 4.5-1.1 1.2-2.4 1.8-4.2 1.8-1.7 0-3.1-.6-4.2-1.8-1.1-1.2-1.7-2.7-1.7-4.5s.6-3.3 1.7-4.5c1.1-1.2 2.5-1.8 4.2-1.8 1.8.1 3.1.7 4.2 1.8zm43.5-3c-1.3-1.4-3-2.1-5.2-2.1-2.4 0-4.2.9-5.4 2.6v-9.6h-3.5v25.7h3.5l.1-10.5c0-1.5.4-2.6 1.2-3.5.8-.9 1.8-1.3 3.2-1.3 1.4 0 2.5.4 3.3 1.3.8.9 1.2 2 1.2 3.5v10.6h3.5V55c0-2.3-.6-4.1-1.9-5.5zM259.1 48h3.5v18.2h-3.5zm0-7.5h3.4v3.4h-3.4z"/></svg> </symbol> <symbol id="icon-caret-right"> <svg xmlns="http://www.w3.org/2000/svg" x="0" y="0" viewBox="0 0 100 100" xml:space="preserve"><path d="M33 99 82.1 50 33 .9z"/></svg> </symbol> </defs> </svg>   <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5P3SZGS" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>  <header id="header_1-0" class="comp header" role="banner" data-tracking-container="true"><a href="#skip-to-content" rel="nocaes" class="skip-link mntl-text-link btn" id="skip-link_1-0" data-tracking-container="true" ><span class="link__wrapper">Skip to content</span></a> <div class="menu-button-container"> <button class="menu-button"> <span class="is-vishidden">Menu</span> <div class="menu-button-inner"> <svg class="icon icon-menu " > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-menu" href="#icon-menu"></use> </svg> <svg class="icon icon-close " > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-close" href="#icon-close"></use> </svg> <div> </button> </div> <div id="logo_1-0" class="comp logo"> <a href="/" rel="home" aria-label="Visit ThoughtCo's homepage"> <span class="is-vishidden">Home</span> <svg class="icon icon-logo " > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-logo" href="#icon-logo"></use> </svg> </a> </div> <nav id="header-nav_1-0" class="comp header-nav" role="navigation"> <ul class="header-nav__list"> <li class="header-nav__list-item"> <a href="https://www.thoughtco.com/sciences-math-4132465" rel="nocaes" class="header-nav__list-item-link" > Science, Tech, Math </a> <ul class="header-nav__sublist"> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/science-4132464" rel="nocaes" class="header-nav__sublist-item-link" > Science </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/math-4133545" rel="nocaes" class="header-nav__sublist-item-link" > Math </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/social-sciences-4133522" rel="nocaes" class="header-nav__sublist-item-link" > Social Sciences </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/computer-science-4133486" rel="nocaes" class="header-nav__sublist-item-link" > Computer Science </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/animals-and-nature-4133421" rel="nocaes" class="header-nav__sublist-item-link" > Animals & Nature </a> </li> </uL> </li> <li class="header-nav__list-item"> <a href="https://www.thoughtco.com/humanities-4133358" rel="nocaes" class="header-nav__list-item-link" > Humanities </a> <ul class="header-nav__sublist"> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/history-and-culture-4133356" rel="nocaes" class="header-nav__sublist-item-link" > History & Culture </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/visual-arts-4132957" rel="nocaes" class="header-nav__sublist-item-link" > Visual Arts </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/literature-4133251" rel="nocaes" class="header-nav__sublist-item-link" > Literature </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/english-4688281" rel="nocaes" class="header-nav__sublist-item-link" > English </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/geography-4133035" rel="nocaes" class="header-nav__sublist-item-link" > Geography </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/philosophy-4133025" rel="nocaes" class="header-nav__sublist-item-link" > Philosophy </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/issues-4133022" rel="nocaes" class="header-nav__sublist-item-link" > Issues </a> </li> </uL> </li> <li class="header-nav__list-item"> <a href="https://www.thoughtco.com/languages-4133094" rel="nocaes" class="header-nav__list-item-link" > Languages </a> <ul class="header-nav__sublist"> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/esl-4133095" rel="nocaes" class="header-nav__sublist-item-link" > English as a Second Language </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/spanish-4133085" rel="nocaes" class="header-nav__sublist-item-link" > Spanish </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/french-4133079" rel="nocaes" class="header-nav__sublist-item-link" > French </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/german-4133073" rel="nocaes" class="header-nav__sublist-item-link" > German </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/italian-4133069" rel="nocaes" class="header-nav__sublist-item-link" > Italian </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/japanese-4133062" rel="nocaes" class="header-nav__sublist-item-link" > Japanese </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/mandarin-4133057" rel="nocaes" class="header-nav__sublist-item-link" > Mandarin </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/russian-4175265" rel="nocaes" class="header-nav__sublist-item-link" > Russian </a> </li> </uL> </li> <li class="header-nav__list-item"> <a href="https://www.thoughtco.com/resources-4132590" rel="nocaes" class="header-nav__list-item-link" > Resources </a> <ul class="header-nav__sublist"> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/for-students-parents-4132588" rel="nocaes" class="header-nav__sublist-item-link" > For Students & Parents </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/for-educators-4132509" rel="nocaes" class="header-nav__sublist-item-link" > For Educators </a> </li> <li class="header-nav__sublist-item"> <a href="https://www.thoughtco.com/for-adult-learners-4132469" rel="nocaes" class="header-nav__sublist-item-link" > For Adult Learners </a> </li> </uL> </li> <li class="header-nav__list-item"> <a href="/about-us-4779650" rel="nocaes" class="header-nav__list-item-link" >About Us</a> </li> </ul> </nav> <div id="general-search_1-0" class="comp general-search" data-tracking-container="true"> <button class="search-icon"> <span class="is-vishidden">Search</span> <svg class="icon icon-search " > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-search" href="#icon-search"></use> </svg> </button> <form class="general-search-form" role="search" action="/search" method="get"> <div class="input-group"> <span class="general-search__close">Close</span> <label for="search-input" class="is-vishidden">Search the site</label> <input type="text" name="q" id="search-input" class="general-search-input" placeholder="Search here..." type="text" required="required" value="" tabindex="-1"> <button class="btn btn-go" tabindex="-1"> <span class="is-vishidden">GO</span> <svg class="icon icon-search " > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-search" href="#icon-search"></use> </svg> </button> </div> </form> </div> <div class="header-nav-panel"> <nav id="fullscreen-nav_1-0" class="comp fullscreen-nav fullscreen-nav-alternate" role="navigation" data-tracking-container="true"> <ul class="fullscreen-nav-list"> <li class="fullscreen-nav-list-item" tabindex="0"> <div class="fullscreen-nav-title fullscreen-nav-title--science-tech-math" > <div> Science, Tech, Math </div> <svg class="icon icon-caret-down " > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-caret-down" href="#icon-caret-down"></use> </svg> </div> <ul class="fullscreen-nav-sub"> <li><a href="https://www.thoughtco.com/science-4132464" rel="nocaes" >Science</a></li> <li><a href="https://www.thoughtco.com/math-4133545" rel="nocaes" >Math</a></li> <li><a href="https://www.thoughtco.com/social-sciences-4133522" rel="nocaes" >Social Sciences</a></li> <li><a href="https://www.thoughtco.com/computer-science-4133486" rel="nocaes" >Computer Science</a></li> <li><a href="https://www.thoughtco.com/animals-and-nature-4133421" rel="nocaes" >Animals & Nature</a></li> </uL> </li> <li class="fullscreen-nav-list-item" tabindex="0"> <div class="fullscreen-nav-title fullscreen-nav-title--humanities" > <div> Humanities </div> <svg class="icon icon-caret-down " > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-caret-down" href="#icon-caret-down"></use> </svg> </div> <ul class="fullscreen-nav-sub"> <li><a href="https://www.thoughtco.com/history-and-culture-4133356" rel="nocaes" >History & Culture</a></li> <li><a href="https://www.thoughtco.com/visual-arts-4132957" rel="nocaes" >Visual Arts</a></li> <li><a href="https://www.thoughtco.com/literature-4133251" rel="nocaes" >Literature</a></li> <li><a href="https://www.thoughtco.com/english-4688281" rel="nocaes" >English</a></li> <li><a href="https://www.thoughtco.com/geography-4133035" rel="nocaes" >Geography</a></li> <li><a href="https://www.thoughtco.com/philosophy-4133025" rel="nocaes" >Philosophy</a></li> <li><a href="https://www.thoughtco.com/issues-4133022" rel="nocaes" >Issues</a></li> </uL> </li> <li class="fullscreen-nav-list-item" tabindex="0"> <div class="fullscreen-nav-title fullscreen-nav-title--languages" > <div> Languages </div> <svg class="icon icon-caret-down " > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-caret-down" href="#icon-caret-down"></use> </svg> </div> <ul class="fullscreen-nav-sub"> <li><a href="https://www.thoughtco.com/esl-4133095" rel="nocaes" >English as a Second Language</a></li> <li><a href="https://www.thoughtco.com/spanish-4133085" rel="nocaes" >Spanish</a></li> <li><a href="https://www.thoughtco.com/french-4133079" rel="nocaes" >French</a></li> <li><a href="https://www.thoughtco.com/german-4133073" rel="nocaes" >German</a></li> <li><a href="https://www.thoughtco.com/italian-4133069" rel="nocaes" >Italian</a></li> <li><a href="https://www.thoughtco.com/japanese-4133062" rel="nocaes" >Japanese</a></li> <li><a href="https://www.thoughtco.com/mandarin-4133057" rel="nocaes" >Mandarin</a></li> <li><a href="https://www.thoughtco.com/russian-4175265" rel="nocaes" >Russian</a></li> </uL> </li> <li class="fullscreen-nav-list-item" tabindex="0"> <div class="fullscreen-nav-title fullscreen-nav-title--resources" > <div> Resources </div> <svg class="icon icon-caret-down " > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-caret-down" href="#icon-caret-down"></use> </svg> </div> <ul class="fullscreen-nav-sub"> <li><a href="https://www.thoughtco.com/for-students-parents-4132588" rel="nocaes" >For Students & Parents</a></li> <li><a href="https://www.thoughtco.com/for-educators-4132509" rel="nocaes" >For Educators</a></li> <li><a href="https://www.thoughtco.com/for-adult-learners-4132469" rel="nocaes" >For Adult Learners</a></li> </uL> </li> <li> <ul id="contact-nav_1-0" class="comp contact-nav"> <li class="contact-nav__nav-item"><a href="/about-us-4779650" rel="nocaes" >About Us</a></li> <li class="contact-nav__nav-item"><a href="/about-us-4779650#toc-contact-us" rel="nocaes" >Contact Us</a></li> <li class="contact-nav__nav-item"><a href="/about-us-4779650#toc-editorial-guidelines" rel="nocaes" >Editorial Guidelines</a></li> <li class="contact-nav__nav-item"><a href="https://www.dotdashmeredith.com/brands-privacy" target="_blank" rel="noopener nocaes" >Privacy Policy</a></li> </ul> </li> </uL> </nav> </div> </header><main id="main" class="loc main" role="main"><iframe id="height-change-listener" role="none" tabindex="-1" src="about:blank" aria-hidden="true"></iframe> <div id="skip-to-content" class="jump-link"></div> <div id="image-nav_1-0" class="comp image-nav"><div class="image-nav-items"> <a href="https://www.thoughtco.com/sciences-math-4132465" rel="nocaes" class="list-item mntl-text-link science" id="list-item_1-0" data-tracking-container="true" ><img class=" universal-image__image" src="/static/5.14.0/images/hp-science,tech,math.png" width="0" height="0" alt="science, tech, math" role="" data-expand="0" data-src="" /> <span id="display-name_1-0" class="comp display-name mntl-text-block">Science, Tech, Math</span></a> <a href="https://www.thoughtco.com/humanities-4133358" rel="nocaes" class="list-item mntl-text-link humanities" id="list-item_2-0" data-tracking-container="true" ><img class=" universal-image__image" src="/static/5.14.0/images/hp-humanities.png" width="0" height="0" alt="humanities" role="" data-expand="0" data-src="" /> <span id="display-name_2-0" class="comp display-name mntl-text-block">Humanities</span></a> <a href="https://www.thoughtco.com/languages-4133094" rel="nocaes" class="list-item mntl-text-link languages" id="list-item_3-0" data-tracking-container="true" ><img class=" universal-image__image" src="/static/5.14.0/images/hp-languages.png" width="0" height="0" alt="languages" role="" data-expand="0" data-src="" /> <span id="display-name_3-0" class="comp display-name mntl-text-block">Languages</span></a> <a href="https://www.thoughtco.com/resources-4132590" rel="nocaes" class="list-item mntl-text-link resources" id="list-item_4-0" data-tracking-container="true" ><img class=" universal-image__image" src="/static/5.14.0/images/hp-resources.png" width="0" height="0" alt="resources" role="" data-expand="0" data-src="" /> <span id="display-name_4-0" class="comp display-name mntl-text-block">Resources</span></a> </div></div> <section id="article-columns_1-0" class="comp article-columns mntl-block" data-tracking-container="true"><ul id="article-columns-list_1-0" class="comp article-columns-list mntl-block with-button"><li id="article-columns-item_1-0" class="comp article-columns-item mntl-block"><a href="https://www.thoughtco.com/sciences-math-4132465" rel="nocaes" class="section-title mntl-text-link " id="section-title_1-0" data-tracking-container="true" ><span class="link__wrapper">Science, Tech, Math</span></a> <ul id="block-list_1-0" class="comp block-list mntl-block" data-tracking-container="true"><li id="block-list-item_1-0" class="comp block-list-item mntl-block g-item"><a id="block_1-0" class="comp block block-small " data-doc-id="4158142" href="https://www.thoughtco.com/why-mathematics-is-a-language-4158142" data-ordinal="1"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/9YToAm2-RaC2jzMdZhprfNpIEy0=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/geometric-shapes-and-mathematics-in-speech-bubble-145166172-5a6de59a6edd650036054170.jpg" width="261" height="174" alt="The symbols used in mathematics may be used to construct sentences." class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/9YToAm2-RaC2jzMdZhprfNpIEy0=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/geometric-shapes-and-mathematics-in-speech-bubble-145166172-5a6de59a6edd650036054170.jpg" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="The symbols used in mathematics may be used to construct sentences." /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="Math"></div> <span class="block-title">Why Mathematics Is a Language</span> </div> </a></li> <li id="block-list-item_2-0" class="comp block-list-item mntl-block g-item"><a id="block_2-0" class="comp block block-small " data-doc-id="2086556" href="https://www.thoughtco.com/magical-multiplication-tricks-2086556" data-ordinal="2"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/0vmsh0kZOpU2SdVajMfAPRhG_MQ=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/GettyImages-996199452-0c5af30a1a3a42c2919903512152a502.jpg" width="261" height="174" alt="multiplication tables on a chalk board" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/0vmsh0kZOpU2SdVajMfAPRhG_MQ=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/GettyImages-996199452-0c5af30a1a3a42c2919903512152a502.jpg" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="multiplication tables on a chalk board" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="Math"></div> <span class="block-title">10 Magical Multiplication Tricks to Teach Kids to Multiply</span> </div> </a></li> <li id="block-list-item_3-0" class="comp block-list-item mntl-block g-item"><a id="block_3-0" class="comp block block-small " data-doc-id="2311988" href="https://www.thoughtco.com/solving-distance-speed-rate-time-problems-2311988" data-ordinal="3"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/hPUZyiAMvTnvsiPCclKrdN7Jb4Q=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/GettyImages-482886745-57b7892e5f9b58cdfdfbd25f.jpg" width="261" height="174" alt="Distance, rate, and time relationships are used to determine how fast a vehicle is going or how far it has traveled." class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/hPUZyiAMvTnvsiPCclKrdN7Jb4Q=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/GettyImages-482886745-57b7892e5f9b58cdfdfbd25f.jpg" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="Distance, rate, and time relationships are used to determine how fast a vehicle is going or how far it has traveled." /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="Pre Algebra & Algebra"></div> <span class="block-title">Solving Distance, Rate, and Time Problems</span> </div> </a></li> <li id="block-list-item_4-0" class="comp block-list-item mntl-block g-item"><a id="block_4-0" class="comp block block-small " data-doc-id="4132465" href="https://www.thoughtco.com/sciences-math-4132465" data-ordinal="4"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/veJDIIL8JI9LMDghqEaETHeujxM=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/tax1_images_science-58a22d0f68a0972917bfb52a.png" width="261" height="174" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/veJDIIL8JI9LMDghqEaETHeujxM=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/tax1_images_science-58a22d0f68a0972917bfb52a.png" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="ThoughtCo"></div> <span class="block-title">Science, Technology, and Math</span> </div> </a></li></ul> <a href="https://www.thoughtco.com/sciences-math-4132465" rel="nocaes" class="column-btn mntl-text-link " id="column-btn_1-0" data-tracking-container="true" ><span class="link__wrapper">All Science, Tech, Math</span> <svg class="icon icon-caret-right text-btn-icon" > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-caret-right" href="#icon-caret-right"></use> </svg></a></li> <li id="article-columns-item_2-0" class="comp article-columns-item mntl-block"><a href="https://www.thoughtco.com/humanities-4133358" rel="nocaes" class="section-title mntl-text-link " id="section-title_2-0" data-tracking-container="true" ><span class="link__wrapper">Humanities</span></a> <ul id="block-list_2-0" class="comp block-list mntl-block" data-tracking-container="true"><li id="block-list-item_5-0" class="comp block-list-item mntl-block g-item"><a id="block_5-0" class="comp block block-small " data-doc-id="4151934" href="https://www.thoughtco.com/jules-verne-biography-4151934" data-ordinal="1"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/__YHN1icw5dW3WrTyypudEWcMI4=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/jules-verne-s--1828-1905--study-in-jules-verne-house-museum--amiens--picardy--france-513009903-59cd2ea8519de20012406010.jpg" width="261" height="174" alt="Jules Verne's (1828-1905) study in Jules Verne house-museum, Amiens, Picardy, France" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/__YHN1icw5dW3WrTyypudEWcMI4=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/jules-verne-s--1828-1905--study-in-jules-verne-house-museum--amiens--picardy--france-513009903-59cd2ea8519de20012406010.jpg" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="Jules Verne's (1828-1905) study in Jules Verne house-museum, Amiens, Picardy, France" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="Literature"></div> <span class="block-title">Jules Verne: His Life and Writings</span> </div> </a></li> <li id="block-list-item_6-0" class="comp block-list-item mntl-block g-item"><a id="block_6-0" class="comp block block-small " data-doc-id="2985145" href="https://www.thoughtco.com/understand-shakespeare-words-2985145" data-ordinal="2"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/RynZEasCXhD9HqwPRXPJrdjQ7Ok=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/GettyImages-183302768-58a0e53e5f9b58819c1e774d.jpg" width="261" height="174" alt="Fingers on top of the text of Hamlet" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/RynZEasCXhD9HqwPRXPJrdjQ7Ok=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/GettyImages-183302768-58a0e53e5f9b58819c1e774d.jpg" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="Fingers on top of the text of Hamlet" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="Shakespeare"></div> <span class="block-title">Yes, You Can Understand Shakespearean English</span> </div> </a></li> <li id="block-list-item_7-0" class="comp block-list-item mntl-block g-item"><a id="block_7-0" class="comp block block-small " data-doc-id="626333" href="https://www.thoughtco.com/grimms-fairy-tales-and-other-versions-626333" data-ordinal="3"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/Cn98gbIi7l6VGQsXwBjCRZjvdLQ=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/468877701-56a140553df78cf77268d236.jpg" width="261" height="174" alt="Cinderella and Prince Charming" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/Cn98gbIi7l6VGQsXwBjCRZjvdLQ=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/468877701-56a140553df78cf77268d236.jpg" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="Cinderella and Prince Charming" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="Children's Books"></div> <span class="block-title">Traditional Fairy Tales from The Brothers Grimm</span> </div> </a></li> <li id="block-list-item_8-0" class="comp block-list-item mntl-block g-item"><a id="block_8-0" class="comp block block-small " data-doc-id="4133358" href="https://www.thoughtco.com/humanities-4133358" data-ordinal="4"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/zBDVxVbdk3CRIonSHdURqD_-mA8=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/tax1_images_humanities-58a22d0f68a0972917bfb52c.png" width="261" height="174" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/zBDVxVbdk3CRIonSHdURqD_-mA8=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/tax1_images_humanities-58a22d0f68a0972917bfb52c.png" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="ThoughtCo"></div> <span class="block-title">Humanities</span> </div> </a></li></ul> <a href="https://www.thoughtco.com/humanities-4133358" rel="nocaes" class="column-btn mntl-text-link " id="column-btn_2-0" data-tracking-container="true" ><span class="link__wrapper">All Humanities</span> <svg class="icon icon-caret-right text-btn-icon" > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-caret-right" href="#icon-caret-right"></use> </svg></a></li> <li id="article-columns-item_3-0" class="comp article-columns-item mntl-block"><a href="https://www.thoughtco.com/languages-4133094" rel="nocaes" class="section-title mntl-text-link " id="section-title_3-0" data-tracking-container="true" ><span class="link__wrapper">Languages</span></a> <ul id="block-list_3-0" class="comp block-list mntl-block" data-tracking-container="true"><li id="block-list-item_9-0" class="comp block-list-item mntl-block g-item"><a id="block_9-0" class="comp block block-small " data-doc-id="3078120" href="https://www.thoughtco.com/telling-time-in-spanish-3078120" data-ordinal="1"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/4pA6nlfzvIQchid6vsmaN_C_8JY=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/government-clock-58b831aa3df78c060e6534d1.jpeg" width="261" height="174" alt="clock in Spain" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/4pA6nlfzvIQchid6vsmaN_C_8JY=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/government-clock-58b831aa3df78c060e6534d1.jpeg" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="clock in Spain" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="Spanish"></div> <span class="block-title">How To Tell Time in Spanish</span> </div> </a></li> <li id="block-list-item_10-0" class="comp block-list-item mntl-block g-item"><a id="block_10-0" class="comp block block-small " data-doc-id="1364615" href="https://www.thoughtco.com/french-pronunciation-mistakes-and-difficulties-1364615" data-ordinal="2"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/iAAa-MoSU4x41QV3hjAUePEjYGk=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/GettyImages-487685939-5843aea33df78c02304c0aea.jpg" width="261" height="174" alt="students talking" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/iAAa-MoSU4x41QV3hjAUePEjYGk=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/GettyImages-487685939-5843aea33df78c02304c0aea.jpg" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="students talking" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="Pronunciation & Conversation"></div> <span class="block-title">Top French Pronunciation Mistakes </span> </div> </a></li> <li id="block-list-item_11-0" class="comp block-list-item mntl-block g-item"><a id="block_11-0" class="comp block block-small " data-doc-id="2279455" href="https://www.thoughtco.com/chinese-language-2279455" data-ordinal="3"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/4pYZ6guOlECazgE8b2a7_69EKx8=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/tourists-admiring-the-hong-kong-skyline-568700513-59dfcb00d963ac0011e83902.jpg" width="261" height="174" alt="Tourists admiring the Hong Kong skyline" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/4pYZ6guOlECazgE8b2a7_69EKx8=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/tourists-admiring-the-hong-kong-skyline-568700513-59dfcb00d963ac0011e83902.jpg" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="Tourists admiring the Hong Kong skyline" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="Mandarin"></div> <span class="block-title">An Explanation of the Various Chinese Languages</span> </div> </a></li> <li id="block-list-item_12-0" class="comp block-list-item mntl-block g-item"><a id="block_12-0" class="comp block block-small " data-doc-id="4133094" href="https://www.thoughtco.com/languages-4133094" data-ordinal="4"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/EyiaV6hMTcEJG9hKuH3a2BvvIMQ=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/tax2_image_languages-58a22d1468a0972917bfb54c.png" width="261" height="174" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/EyiaV6hMTcEJG9hKuH3a2BvvIMQ=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/tax2_image_languages-58a22d1468a0972917bfb54c.png" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="ThoughtCo"></div> <span class="block-title">Resources</span> </div> </a></li></ul> <a href="https://www.thoughtco.com/languages-4133094" rel="nocaes" class="column-btn mntl-text-link " id="column-btn_3-0" data-tracking-container="true" ><span class="link__wrapper">All Languages</span> <svg class="icon icon-caret-right text-btn-icon" > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-caret-right" href="#icon-caret-right"></use> </svg></a></li> <li id="article-columns-item_4-0" class="comp article-columns-item mntl-block"><a href="https://www.thoughtco.com/resources-4132590" rel="nocaes" class="section-title mntl-text-link " id="section-title_4-0" data-tracking-container="true" ><span class="link__wrapper">Resources</span></a> <ul id="block-list_4-0" class="comp block-list mntl-block" data-tracking-container="true"><li id="block-list-item_13-0" class="comp block-list-item mntl-block g-item"><a id="block_13-0" class="comp block block-small " data-doc-id="1098385" href="https://www.thoughtco.com/study-secrets-1098385" data-ordinal="1"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/ahLpwwQgNJ5mYRHCQaMOsri9mkc=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/GettyImages-175138224-5a1fcda022fa3a0037c578fe.jpg" width="261" height="174" alt="Girl reads book on in between two book shelves." class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/ahLpwwQgNJ5mYRHCQaMOsri9mkc=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/GettyImages-175138224-5a1fcda022fa3a0037c578fe.jpg" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="Girl reads book on in between two book shelves." /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="Distance Learning"></div> <span class="block-title">5 Study Secrets to Ace Your Exams</span> </div> </a></li> <li id="block-list-item_14-0" class="comp block-list-item mntl-block g-item"><a id="block_14-0" class="comp block block-small " data-doc-id="31425" href="https://www.thoughtco.com/what-is-adult-learning-31425" data-ordinal="2"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/sEU2lRZ6pm-ueYN9jxO1klzmsBY=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/ASUMH-589590963df78caebc91eecf.JPG" width="261" height="174" alt="Arkansas State University" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/sEU2lRZ6pm-ueYN9jxO1klzmsBY=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/ASUMH-589590963df78caebc91eecf.JPG" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="Arkansas State University" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="For Adult Learners"></div> <span class="block-title">The Basics of Adult Learning</span> </div> </a></li> <li id="block-list-item_15-0" class="comp block-list-item mntl-block g-item"><a id="block_15-0" class="comp block block-small " data-doc-id="31734" href="https://www.thoughtco.com/when-to-use-uppercase-capital-letters-31734" data-ordinal="3"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/GR11vBFldPkedaPVgKMbpCXQ0KU=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/n-244097_1920-5c92bcd3c9e77c00018fb627.jpg" width="261" height="174" alt="Capital "N" key ring attached to a red book close up." class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/GR11vBFldPkedaPVgKMbpCXQ0KU=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/n-244097_1920-5c92bcd3c9e77c00018fb627.jpg" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" alt="Capital "N" key ring attached to a red book close up." /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="Tips For Adult Students"></div> <span class="block-title">When to Use Uppercase or Capital Letters</span> </div> </a></li> <li id="block-list-item_16-0" class="comp block-list-item mntl-block g-item"><a id="block_16-0" class="comp block block-small " data-doc-id="4132590" href="https://www.thoughtco.com/resources-4132590" data-ordinal="4"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:66.6%;"> <img data-src="https://www.thoughtco.com/thmb/dYb1G7w5jIXp2rrEZRqHP3pcjH4=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/tax1_images_resources-58a22d0f68a0972917bfb52b.png" width="261" height="174" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/dYb1G7w5jIXp2rrEZRqHP3pcjH4=/261x174/filters:no_upscale():max_bytes(150000):strip_icc()/tax1_images_resources-58a22d0f68a0972917bfb52b.png" width="261" height="174" class="img--noscript block-image mntl-image universal-image__image" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="ThoughtCo"></div> <span class="block-title">Resources</span> </div> </a></li></ul> <a href="https://www.thoughtco.com/resources-4132590" rel="nocaes" class="column-btn mntl-text-link " id="column-btn_4-0" data-tracking-container="true" ><span class="link__wrapper">All Resources</span> <svg class="icon icon-caret-right text-btn-icon" > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-caret-right" href="#icon-caret-right"></use> </svg></a></li></ul></section> <section id="spotlight-with-title_1-0" class="comp spotlight-with-title spotlight mntl-sc-page right-rail spotlight-full" data-sc-sticky-offset="85" data-sc-breakpoint="50em" data-tracking-container="true" data-sc-content-positions="[1]"><h2 id="section-title_5-0" class="comp section-title"> <span>BEHIND THE NEWS</span> </h2><div id="spotlight-lists_1-0" class="comp spotlight-lists spotlight-list spotlight-blocks mntl-block"><div id="spotlight-block-item_1-0" class="comp spotlight-block-item mntl-block"><a id="hero-block_1-0" class="comp hero-block block block-large " data-doc-id href="https://www.thoughtco.com/why-presidents-only-serve-two-terms-3367979"> <div class="loc block-media"><div class="img-placeholder" style="padding-bottom:100.0%;"> <img data-src="https://www.thoughtco.com/thmb/pxZRFGwx2fezmajrK2SwNWWzgU4=/300x300/filters:no_upscale():max_bytes(150000):strip_icc()/Why-presidents-only-serve-two-terms-3367979_final_r2-4998a573c08d4466bf6a8ca13b05040a.png" width="300" height="300" alt="How long can a president stay in office? illustration" class="lazyload block-image mntl-image universal-image__image" data-expand="300" /> <noscript> <img src="https://www.thoughtco.com/thmb/pxZRFGwx2fezmajrK2SwNWWzgU4=/300x300/filters:no_upscale():max_bytes(150000):strip_icc()/Why-presidents-only-serve-two-terms-3367979_final_r2-4998a573c08d4466bf6a8ca13b05040a.png" width="300" height="300" class="img--noscript block-image mntl-image universal-image__image" alt="How long can a president stay in office? illustration" /> </noscript> </div> </div> <div class="block-content"> <div class="block-kicker" data-kicker="The U. S. Government"></div> <span class="block-title">How Many Years Can a President Serve in the White House?</span> <div class="block-data-excerpt" data-excerpt="Find out why United States presidents are limited to two four-year terms in the White House. Learn how a president could serve 10 years in office."></div> </div> </a></div> <div id="spotlight-secondary_1-0" class="comp spotlight-secondary mntl-block"><div id="secondary-blocks_1-0" class="comp secondary-blocks mntl-block"><a id="secondary_1-0" class="comp secondary block no-image" data-doc-id href="https://www.thoughtco.com/totalitarianism-authoritarianism-fascism-4147699"> <div class="block-content"> <div class="block-kicker" data-kicker="The 20th Century"></div> <span class="block-title">The Difference Between Totalitarianism, Authoritarianism, and Fascism</span> </div> </a></div> <div id="secondary-blocks_2-0" class="comp secondary-blocks mntl-block"><a id="secondary_2-0" class="comp secondary block no-image" data-doc-id href="https://www.thoughtco.com/what-is-the-seniority-system-3368073"> <div class="block-content"> <div class="block-kicker" data-kicker="The U. S. Government"></div> <span class="block-title">What Is the Seniority System in Congress?</span> </div> </a></div></div></div> <div class="spotlight-billboard"> <div id="ref-billboard1-sticky_1-0" class="comp ref-billboard1-sticky mntl-block" data-parent=".spotlight"><div id="mm-ads-sc-sticky-square-ad_1-0" class="comp mm-ads-sc-sticky-square-ad mm-ads-squareFlex1-sticky mm-ads-sc-sticky-square scads-to-load right-rail__item" data-height="650" style="height: 650px;"><div id="mm-ads-sc-sticky-square-ad_2-0" class="comp mm-ads-sc-sticky-square-ad mm-ads-square mm-ads-gpt-adunit gpt square "> <div id="square-flex-1" class="wrapper" ></div> </div></div></div> </div> </section> </main><footer id="footer_1-0" class="comp footer mntl-footer" role="contentinfo" data-tracking-container="true"> <div class="mntl-footer__inner"> <div class="mntl-footer__primary"> <div class="mntl-footer__logo"> <a href="/" rel="home nocaes" id="mntl-logo_1-0" aria-label="Visit the homepage" > <div class="is-screenreader-only">ThoughtCo</div> <svg class="icon icon-logo " > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-logo" href="#icon-logo"></use> </svg></a> </div> <div class="mntl-footer__social"> <div id="mntl-footer-social_1-0" class="comp mntl-footer-social reference-social-nav mntl-social-nav" data-tracking-container="true"> <h2 class="social-nav__title">Follow Us</h2> <ul class="social-nav__list"> <li class="social-nav__item social-nav__item--facebook"> <a href="http://www.facebook.com/thoughtcodotcom" target="_blank" rel="noopener nocaes" class="social-nav__link social-nav__link--facebook" aria-label="Visit ThoughtCo's Facebook" > <svg class="icon icon-facebook social-nav__icon" > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-facebook" href="#icon-facebook"></use> </svg> </a> </li> <li class="social-nav__item social-nav__item--flipboard"> <a href="https://flipboard.com/@thoughtco?utm_source=thoughtco&utm_medium=follow&utm_campaign=tools" target="_blank" rel="noopener nocaes" class="social-nav__link social-nav__link--flipboard" aria-label="Visit ThoughtCo's Flipboard" > <svg class="icon icon-flipboard social-nav__icon" > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-flipboard" href="#icon-flipboard"></use> </svg> </a> </li> </ul> </div> </div> </div> <div class="mntl-footer__secondary"> <nav id="mntl-footer-nav_1-0" class="comp mntl-footer-nav mntl-block" aria-label="Footer"><ul id="mntl-block_1-0" class="comp mntl-block mntl-footer-nav__list"><li id="mntl-footer-nav__list-item_1-0" class="comp mntl-footer-nav__list-item mntl-block"><a href="https://www.thoughtco.com/sciences-math-4132465" rel="nocaes" class="mntl-text-link text-label-300 global-link" id="mntl-text-link_1-0" data-tracking-container="true" ><span class="link__wrapper">Science, Tech, Math</span></a></li> <li id="mntl-footer-nav__list-item_2-0" class="comp mntl-footer-nav__list-item mntl-block"><a href="https://www.thoughtco.com/humanities-4133358" rel="nocaes" class="mntl-text-link text-label-300 global-link" id="mntl-text-link_2-0" data-tracking-container="true" ><span class="link__wrapper">Humanities</span></a></li> <li id="mntl-footer-nav__list-item_3-0" class="comp mntl-footer-nav__list-item mntl-block"><a href="https://www.thoughtco.com/languages-4133094" rel="nocaes" class="mntl-text-link text-label-300 global-link" id="mntl-text-link_3-0" data-tracking-container="true" ><span class="link__wrapper">Languages</span></a></li> <li id="mntl-footer-nav__list-item_4-0" class="comp mntl-footer-nav__list-item mntl-block"><a href="https://www.thoughtco.com/resources-4132590" rel="nocaes" class="mntl-text-link text-label-300 global-link" id="mntl-text-link_4-0" data-tracking-container="true" ><span class="link__wrapper">Resources</span></a></li></ul></nav><ul id="mntl-footer-links_1-0" class="comp mntl-footer-links footer-links"> <li class="mntl-footer-links__item "> <a href="/about-us-4779650" rel="nocaes" data-type="ourStory" data-ordinal="1" class="mntl-footer-links__link text-utility-200 global-link" data-component="footerLinks" data-source="footerLinks" > About Us </a> </li> <li class="mntl-footer-links__item "> <a href="https://www.dotdashmeredith.com/advertising" target="_blank" rel="noopener nofollow nocaes" data-type="advertise" data-ordinal="1" class="mntl-footer-links__link text-utility-200 global-link" data-component="footerLinks" data-source="footerLinks" > Advertise </a> </li> <li class="mntl-footer-links__item "> <a href="https://www.dotdashmeredith.com/careers" target="_blank" rel="noopener nofollow nocaes" data-type="careersAtDotDashMeredith" data-ordinal="1" class="mntl-footer-links__link text-utility-200 global-link" data-component="footerLinks" data-source="footerLinks" > Careers </a> </li> <li class="mntl-footer-links__item "> <a href="https://www.dotdashmeredith.com/brands-privacy" target="_blank" rel="noopener nofollow nocaes" data-type="privacyPolicy" data-ordinal="1" class="mntl-footer-links__link text-utility-200 global-link" data-component="footerLinks" data-source="footerLinks" > Privacy Policy </a> </li> <li class="mntl-footer-links__item "> <a href="/about-us-4779650#toc-editorial-guidelines" rel="nocaes" data-type="editorialGuidelines" data-ordinal="1" class="mntl-footer-links__link text-utility-200 global-link" data-component="footerLinks" data-source="footerLinks" > Editorial Guidelines </a> </li> <li class="mntl-footer-links__item "> <a href="/about-us-4779650#toc-contact-us" rel="nocaes" data-type="contact" data-ordinal="1" class="mntl-footer-links__link text-utility-200 global-link" data-component="footerLinks" data-source="footerLinks" > Contact </a> </li> <li class="mntl-footer-links__item "> <a href="https://www.dotdashmeredith.com/brands-termsofservice" target="_blank" rel="noopener nofollow nocaes" data-type="termsOfService" data-ordinal="1" class="mntl-footer-links__link text-utility-200 global-link" data-component="footerLinks" data-source="footerLinks" > Terms of Service </a> </li> <li class="mntl-footer-links__item mntl-truste-badge-wrapper"> <div class="loc truste-badge"><div id="mntl-universal-truste-badge_1-0" class="comp mntl-universal-truste-badge mntl-block"><a href="//privacy.truste.com/privacy-seal/validation?rid=e166d0ee-e663-4ad0-9384-f5bd78093a89" target="_blank" rel="noopener nocaes" class="mntl-truste-badge-link" id="mntl-universal-truste-badge_1-0-link" data-tracking-container="true" > <img class="mntl-truste-badge-image lazyload" alt="Access TRUSTe's Enterprise Privacy Certification program" data-src="//privacy-policy.truste.com/privacy-seal/seal?rid=e166d0ee-e663-4ad0-9384-f5bd78093a89" width="100" height="32" /> </a></div> </div> </li> </ul> </div> </div> <div class="loc footer-bottom"><div id="mntl-dotdash-universal-nav_1-0" class="comp mntl-dotdash-universal-nav mntl-carbon-dotdash-universal-nav" data-tracking-container="true"> <div class="mntl-dotdash-universal-nav__content"> <svg class="icon mntl-dotdash-universal-nav__logo " > <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#mntl-dotdash-universal-nav__logo" href="#mntl-dotdash-universal-nav__logo"></use> </svg> <div class="mntl-dotdash-universal-nav__wrapper"> <div class="mntl-dotdash-universal-nav__text"> ThoughtCo is part of the <a href="https://www.dotdashmeredith.com" target="_blank" rel="noopener nofollow nocaes" class="mntl-dotdash-universal-nav__text--link" >Dotdash Meredith</a> publishing family. </div> </div> </div> </div> </div></footer><svg class="is-hidden"> <defs> <symbol id="mntl-sc-block-starrating-icon"> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20"> <path d="M0,0v20h20V0H0z M14.2,12.2l1.1,6.3l-5.4-3.2l-5.1,3.2l1-6.3L1.4,8l5.9-0.8l2.6-5.8l2.7,5.8L18.5,8L14.2,12.2z"/> </svg> </symbol> </defs> </svg><script type="text/javascript" data-glb-js="bottom" src="/static/5.14.0/cache/eNqlklFuwyAMhi80i0PsdZdwwCFeHNOB07U9_QiJti6tokl7wdj6_08Y2xVDY-8mVBNy78VN9QJnVBZBKD4nkRf3W-XTdEpKasWxGmVFcYF6you_XTKFAxNdVhPfCIR1LIvvofhvANSn4CwGJ5kj6wFvRKPLev6oUpiFGlnwdgU86uiTQ6QaNRn37KsqKXSouv4J05b8ATEQx8FeB9RIb1yMFsaz4jfrDhIldXUYA2ForiU80_UpT1W9YFCgEGY_7NJnNsUzx9ac62eRuh1ECrW6Sw_aDIyS4hbanI62a8LYljJyv5dtmXDXZlRqMl47tvIwwTtg-ZgxN2LxIMmPsFa-AB-pKeY.min.js" async defer="true"></script> <script type="text/javascript"> Mntl.utilities.scriptsOnLoad(document.querySelectorAll('script[data-glb-js="bottom"]'), function() { var Mntl = window.Mntl || {}; window.Mntl.externalizeLinks.addPlugin(Mntl.externalizeLinkDefaultPlugin); window.Mntl.externalizeLinks.init();}); </script></body> </html>