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Why do heavy objects tend to fall downwards when dropped? How are birds able to fly (and why can鈥檛 I do the same?)? Human beings have long been curious about the world in which we live, striving to identify connections among the phenomenons we witness and to understand how it all works. The field of science has developed over many centuries as a way of studying and understanding the world, beginning with the primitive stage of simply noting important regularities in nature and continuing through the rise of modern science. The modern-day sciences cover a vast range of fields, including biology, chemistry, meteorology, astronomy, physics, and much more.</div> </div> <div class="text-hr text-hr-right border-navy label mt-30 ls-lg">Browse Subcategories</div> <div class="slider js-slider position-relative d-inline-flex align-items-center mw-100 mt-20 category-snap-slider"> <div class="slider-container js-slider-container overflow-hidden d-flex font-14 overflow-hidden text-nowrap mx-5"> <a href="/browse/Astronomy" class="link-white mr-20 mr-sm-30">Astronomy</a> <a href="/browse/Biology" class="link-white mr-20 mr-sm-30">Biology</a> <a href="/browse/Birds-Reptiles-Vertebrates" class="link-white mr-20 mr-sm-30">Birds, Reptiles & Other Vertebrates</a> <a href="/browse/Bugs-Mollusks-Invertebrates" class="link-white mr-20 mr-sm-30">Bugs, Mollusks & Other Invertebrates</a> <a href="/browse/Chemistry" class="link-white mr-20 mr-sm-30">Chemistry</a> <a href="/browse/Earth-Science-Geology-Fossils" class="link-white mr-20 mr-sm-30">Earth Science, Geologic Time & Fossils</a> <a href="/browse/Environment" class="link-white mr-20 mr-sm-30">Environment</a> <a href="/browse/Mammals" class="link-white mr-20 mr-sm-30">Mammals</a> <a href="/browse/Mathematics" class="link-white mr-20 mr-sm-30">Mathematics</a> <a href="/browse/Plants" class="link-white mr-20 mr-sm-30">Plants</a> <a href="/browse/Physics" class="link-white ">Physics</a> </div> <button disabled class="prev-button js-prev-button position-absolute btn btn-circle shadow btn-blue " aria-label="Previous"> <span class="material-icons md-24" data-icon="keyboard_arrow_left"></span> </button> <button disabled class="next-button js-next-button position-absolute btn btn-circle shadow btn-blue " aria-label="Next"> <span class="material-icons md-24" data-icon="keyboard_arrow_right"></span> </button> </div> </div> </div> <div class="container"> <h2 class="label my-30 text-center">Featured content, November 27, 2024</h2> <div class="qa-pinboard-items js-pinboard grid gy-20"> <div class="p-10 d-inline-flex js-pin col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <a href="/list/5-weird-facts-about-venus" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/86/21186-131-2CCA93CC/radar-clouds-Scientists-surface-Venus-computer-image.jpg?w=400&h=225&c=crop" alt="Venus, view of the northern hemisphere based on observations made by the Magellan spacecraft. The Maxwell Montes, Venus' highest mountain range, is the bright spot just below the center of the image. The Montes, and the dark areas above and to its left,a" class="col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="/list/5-weird-facts-about-venus" class="font-weight-bold font-16 lh-sm">5 Weird Facts About Venus</a> <div class="font-serif mt-10 font-14"> Know thy neighboring planet. </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex js-pin col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <a href="/story/is-the-ozone-layer-finally-healing-itself" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/89/93589-131-5028197E/information-image-satellite-high-ozone-layer-Earth-September-2005.jpg?w=400&h=225&c=crop" alt="September 11, 2005, ozone thinning over antarctica reached its maximum extent for the year." class="col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="/story/is-the-ozone-layer-finally-healing-itself" class="font-weight-bold font-16 lh-sm">Is the Ozone Layer Finally Healing Itself?</a> <div class="font-serif mt-10 font-14"> Is there evidence now that the ozone layer is actually healing itself? </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex js-pin col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <a href="/story/what-are-matrices-used-for" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/25/238125-131-80136559/solving-math-problem-paper.jpg?w=400&h=225&c=crop" alt="Solving a math problem with paper. (mathematics, calculation, arithmetic, education, analysis, equations)" class="col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="/story/what-are-matrices-used-for" class="font-weight-bold font-16 lh-sm">What Are Matrices Used For?</a> <div class="font-serif mt-10 font-14"> Learn more about matrices. </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex js-pin col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <a href="/story/the-real-science-behind-frankenstein" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/03/197003-131-F0327079/Frankenstein-Boris-Karloff-James-Whale.jpg?w=400&h=225&c=crop" alt="Frankenstein, Boris Karloff (1931). Directed by James Whale" class="col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="/story/the-real-science-behind-frankenstein" class="font-weight-bold font-16 lh-sm">The Real Science Behind Frankenstein</a> <div class="font-serif mt-10 font-14"> How Mary Shelley鈥檚 imagination came alive. </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex js-pin col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <a href="https://www.britannica.com/science/mathematics" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/54/2354-050-B47B3735/Babylonian-tablet.jpg?w=400&h=225&c=crop" alt="Babylonian mathematical tablet" class="col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="https://www.britannica.com/science/mathematics" class="font-weight-bold font-16 lh-sm">mathematics</a> <div class="font-serif mt-10 font-14"> Mathematics, the science of structure, order, and relation that has evolved from elemental practices of counting, measuring,... </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex js-pin col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <a href="https://www.britannica.com/topic/philosophy-of-science" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/84/87984-050-7C5547FE/Detail-Roman-copy-portrait-bust-Aristotle-Greek.jpg?w=400&h=225&c=crop" alt="Aristotle" class="col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="https://www.britannica.com/topic/philosophy-of-science" class="font-weight-bold font-16 lh-sm">philosophy of science</a> <div class="font-serif mt-10 font-14"> Philosophy of science, the study, from a philosophical perspective, of the elements of scientific inquiry. This article discusses... </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex js-pin col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <a href="https://www.britannica.com/science/control-group" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/mendel-resources/3-130/images/shared/default3.png?v=3.130.14" class="default col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="https://www.britannica.com/science/control-group" class="font-weight-bold font-16 lh-sm">control group</a> <div class="font-serif mt-10 font-14"> Control group, the standard to which comparisons are made in an experiment. Many experiments are designed to include a control... </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex js-pin col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <a href="https://www.britannica.com/science/science" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/42/154842-138-D063918E/Kara-Rogers-difference-Encyclopaedia-Britannica-theory-hypothesis.jpg?w=400&h=225&c=crop" alt="Understanding scientific hypotheses, theories, and models" class="col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="https://www.britannica.com/science/science" class="font-weight-bold font-16 lh-sm">science</a> <div class="font-serif mt-10 font-14"> Science, any system of knowledge that is concerned with the physical world and its phenomena and that entails unbiased observations... </div> </div> </div> </div> </div> </div> <div class="qa-quizzes"> <h2 class="h3 mt-30 mb-20 font-weight-bold">Science Quizzes</h2> <div class="m-n10 "> <div class="slider js-slider position-relative d-inline-flex align-items-center mw-100 card-snap-slider col-100"> <div class="slider-container js-slider-container overflow-hidden d-flex col-100"> <div class="p-10 d-inline-flex col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <a href="/quiz/know-your-marsupials-quiz" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/87/230887-131-00D9C179/red-kangaroo-Macropus-rufus-outback-Queensland-Australia.jpg?w=400&h=225&c=crop" alt="Red kangaroo (Macropus rufus) in the outback of Queensland, Australia. Marsupial" class="col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="/quiz/know-your-marsupials-quiz" class="font-weight-bold font-16 lh-sm">Know Your Marsupials Quiz</a> <div class="font-serif mt-10 font-14"> There are more than 250 species classified as marsupials. This quiz will test what you know about these unique animals. </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <div class="image-icon-sm position-absolute rounded-sm right-10 top-10"> <span class="material-icons font-20" data-icon="image"></span> </div> <a href="/quiz/can-you-identify-these-mammals-a-photo-quiz" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/63/189063-131-EE40599F/species-hedgehog-types-European-pet.jpg?w=400&h=225&c=crop" alt="Western European hedgehog (Erinaceus europaeus) foraging in the leaves on the forest floor. Mammal animal insectivore" class="col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="/quiz/can-you-identify-these-mammals-a-photo-quiz" class="font-weight-bold font-16 lh-sm">Can You Identify These Mammals? A Photo Quiz</a> <div class="font-serif mt-10 font-14"> Do you know a hedgehog from an aardvark? Prove it with this quiz! You鈥檒l be shown a photo, and you鈥檒l need to identify what... </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <div class="image-icon-sm position-absolute rounded-sm right-10 top-10"> <span class="material-icons font-20" data-icon="image"></span> </div> <a href="/quiz/know-your-archimedean-solids-quiz" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/30/230930-131-61106B2B/Truncated-icosahedron-one-of-the-Archimedean-solids.jpg?w=400&h=225&c=crop" alt="Truncated icosahedron, one of the Archimedean solids. A truncated icosahedron has 32 faces: 12 pentagons and 20 hexagons. Soccer balls are traditionally truncated icosahedrons." class="col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="/quiz/know-your-archimedean-solids-quiz" class="font-weight-bold font-16 lh-sm">Know Your Archimedean Solids Quiz</a> <div class="font-serif mt-10 font-14"> There are 13 Archimedean solids, which have two or more types of regular polygons as their faces. All of an Archimedean solid鈥檚... </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <div class="image-icon-sm position-absolute rounded-sm right-10 top-10"> <span class="material-icons font-20" data-icon="image"></span> </div> <a href="/quiz/whats-a-platonic-solid" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/23/230923-131-5B024AF8/Cube-one-of-the-five-Platonic-solids.jpg?w=400&h=225&c=crop" alt="Cube, one of the five Platonic solids. A cube is a polyhedron with six faces, all of which are squares." class="col-100" /> </a> </div> <div class="col"> <div class="card-body text-hyphenate"> <a href="/quiz/whats-a-platonic-solid" class="font-weight-bold font-16 lh-sm">What鈥檚 a Platonic Solid?</a> <div class="font-serif mt-10 font-14"> A Platonic solid is a geometric solid with faces that are identical regular polygons and that all meet at the same three-dimensional... </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <a href="/quiz/the-dog-breed-quiz" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/87/232787-131-33E4C22A/retriever-dog-breeds.jpg?w=400&h=225&c=crop" alt="Various retriever dog breeds sitting in a row. 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Or what animal has the strongest bite? </div> </div> </div> </div> </div> <div class="p-10 d-inline-flex col-100 col-sm-33 col-md-25 "> <div class="card text-normal col-100 "> <div class="card-media position-relative"> <div class="image-icon-sm position-absolute rounded-sm right-10 top-10"> <span class="material-icons font-20" data-icon="image"></span> </div> <a href="/quiz/name-that-dog" style="--aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/13/234213-131-80407AB0/dachshund-dog.jpg?w=400&h=225&c=crop" alt="Dachshund dog with a smooth coat. 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Humankind's fascination with the world beyond Earth has led to many landmark moments in history, as when space exploration took a giant step forward with the advent of technology that allowed humans to successfully travel to the Moon and to build spacecraft capable of exploring the rest of the solar system and beyond.</div> <div class="label mt-20">Articles</div> <ul class="list-unstyled"> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/universe">universe</a> <div class="font-serif">astronomy</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/biography/Valery-Vladimirovich-Polyakov">Valery Vladimirovich Polyakov</a> <div class="font-serif">Soviet cosmonaut</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/place/Great-Red-Spot">Great Red Spot</a> <div class="font-serif">storm system, Jupiter</div> </li> </ul> </div> <div class="col-100 col-sm-33 col-md-25"> <a href="/browse/Biology"> <img loading="lazy" src="https://cdn.britannica.com/mendel/resources/encyclopedia-placeholder.jpg?w=400&h=225&c=crop" alt="subcategory placeholder" class="col-100 mb-15" /> </a> <a href="/browse/Biology" class="font-weight-bold font-16">Biology</a> <div class="font-serif mt-10 line-clamp clamp-3">How do plants feed themselves? How did dogs evolve from wolves? What good is the appendix in humans, anyway? Such questions fall within the domain of biology, which seeks to understand living organisms and their vital processes (although the jury鈥檚 still out on what our appendixes are for). Biology鈥檚 diverse fields include botany, ecology, evolution, genetics, medicine, physiology, and zoology.</div> <div class="label mt-20">Articles</div> <ul class="list-unstyled"> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/genetics">genetics</a> <div class="font-serif"></div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/chordate">chordate</a> <div class="font-serif">animal phylum</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/topic/animal-social-behaviour">animal social behaviour</a> <div class="font-serif"></div> </li> </ul> </div> <div class="col-100 col-sm-33 col-md-25"> <a href="/browse/Birds-Reptiles-Vertebrates"> <img loading="lazy" src="https://cdn.britannica.com/58/26558-004-E2C978A1/Salamander.jpg?w=400&h=225&c=crop" alt="banded fire salamander (Salamandra terrestris)" class="col-100 mb-20" /> </a> <a href="/browse/Birds-Reptiles-Vertebrates" class="font-weight-bold font-16">Birds, Reptiles & Other Vertebrates</a> <div class="font-serif mt-10 line-clamp clamp-3">Although it can be hard to imagine that a peacock and a crocodile have much of anything in common, these animals are actually descendants of the same prehistoric vertebrates. Birds are thought to have descended from carnivorous dinosaurs that began growing feathers by the Late Jurassic Period; thus, birds are technically one lineage of reptiles. This evolutionary link highlights the way in which seemingly incongruous creatures can, in fact, share a common ancestor (though that doesn't mean that we should expect waterfowl and crocodiles to become friends anytime soon).</div> <div class="label mt-20">Articles</div> <ul class="list-unstyled"> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/dinosaur">dinosaur</a> <div class="font-serif">fossil reptile</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/turtle-reptile">turtle</a> <div class="font-serif">reptile</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/bird-animal">bird</a> <div class="font-serif">animal</div> </li> </ul> </div> <div class="col-100 col-sm-33 col-md-25"> <a href="/browse/Bugs-Mollusks-Invertebrates"> <img loading="lazy" src="https://cdn.britannica.com/03/143903-050-DD38BCBE/scanning-electron-micrograph-soybean-cyst-nematode-egg.jpg?w=400&h=225&c=crop" alt="microfauna" class="col-100 mb-20" /> </a> <a href="/browse/Bugs-Mollusks-Invertebrates" class="font-weight-bold font-16">Bugs, Mollusks & Other Invertebrates</a> <div class="font-serif mt-10 line-clamp clamp-3"> Yet, in addition to being critically important鈥攂ecause they naturally recycle decaying matter鈥攊n maintaining balance within the food chain, bugs can also be fascinating creatures, whether in regard to the water strider's ability to run across the surface of water or the assassin bugs' varied and creative means of catching and killing their prey. Mollusks, another group of invertebrates, get less of a bad rap. Their ranks include nearly 100,000 described species of soft-bodied animals that are usually wholly or partly enclosed in a calcium carbonate shell; examples include snails, clams, oysters, squids, and octopuses.</div> <div class="label mt-20">Articles</div> <ul class="list-unstyled"> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/mantid">mantid</a> <div class="font-serif">insect</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/bee">bee</a> <div class="font-serif">insect</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/coral">coral</a> <div class="font-serif">invertebrate</div> </li> </ul> </div> <div class="col-100 col-sm-33 col-md-25"> <a href="/browse/Chemistry"> <img loading="lazy" src="https://cdn.britannica.com/40/7440-004-07959002/cycle.jpg?w=400&h=225&c=crop" alt="geochemical cycle" class="col-100 mb-20" /> </a> <a href="/browse/Chemistry" class="font-weight-bold font-16">Chemistry</a> <div class="font-serif mt-10 line-clamp clamp-3">How do you use raw plant materials to manufacture a best-selling perfume? How do you engineer household products that are compliant with environmentally-oriented guidelines? The answers to these questions require an understanding of the laws of chemistry, the science that deals with the properties, composition, and structure of elements and compounds, as well as the transformations that such substances undergo and the energy that is released or absorbed during those processes. Chemistry is also concerned with the utilization of natural substances and the creation of artificial ones. Over time, more than 8,000,000 different chemical substances, both natural and artificial, have been characterized and produced. Chemistry's vast scope comprises organic, inorganic, physical, analytical, and industrial chemistry, along with biochemistry, environmental chemistry, medicinal chemistry, and much more. Through the dedicated efforts of people such as Robert Boyle, Dmitri Mendeleev, John Dalton, Marie Curie, and Rosalind Franklin, the field of chemistry has led to exciting innovations as well as crucial advances in our understanding of how the world functions, starting with the miniscule and unassuming atom.</div> <div class="label mt-20">Articles</div> <ul class="list-unstyled"> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/neon-chemical-element">neon</a> <div class="font-serif">chemical element</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/biography/Frederic-and-Irene-Joliot-Curie">Fr茅d茅ric and Ir猫ne Joliot-Curie</a> <div class="font-serif">French chemists</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/noble-gas">noble gas</a> <div class="font-serif">chemical elements</div> </li> </ul> </div> <div class="col-100 col-sm-33 col-md-25"> <a href="/browse/Earth-Science-Geology-Fossils"> <img loading="lazy" src="https://cdn.britannica.com/57/143857-050-EAA84535/Neuropteris-ovata-Hoffmann-seed-fern-Ohio.jpg?w=400&h=225&c=crop" alt="seed fern" class="col-100 mb-20" /> </a> <a href="/browse/Earth-Science-Geology-Fossils" class="font-weight-bold font-16">Earth Science, Geologic Time & Fossils</a> <div class="font-serif mt-10 line-clamp clamp-3">Planet Earth has billions of years of history, from the time when it was an inhospitable ball of hot magma to when its surface stabilized into a variety of diverse zones capable of supporting many life-forms. Many are the species that lived through the various geologic eras and left a trace of their existence in the fossils that we study today. But Earth is never done settling, as we can see from the earthquakes, tsunamis, volcanic eruptions, and other phenomena manifested in Earth鈥檚 crust, oceans, and atmosphere.</div> <div class="label mt-20">Articles</div> <ul class="list-unstyled"> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/Batodonoides">Batodonoides</a> <div class="font-serif">fossil mammal genus</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/trilobite">trilobite</a> <div class="font-serif">fossil arthropod</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/stromatolite">stromatolite</a> <div class="font-serif">geology</div> </li> </ul> </div> <div class="col-100 col-sm-33 col-md-25"> <a href="/browse/Environment"> <img loading="lazy" src="https://cdn.britannica.com/09/102009-050-81C6D817/Earths-hot-spots-of-biodiversity.jpg?w=400&h=225&c=crop" alt="terrestrial hot spots of biodiversity" class="col-100 mb-20" /> </a> <a href="/browse/Environment" class="font-weight-bold font-16">Environment</a> <div class="font-serif mt-10 line-clamp clamp-3">Biological diversity is key to a healthy ecosystem, whether it鈥檚 a small biological community or the global biosphere. Ecology, which studies the relationships between organisms and their environment, is an invaluable science that helps us understand what allows an ecological community to thrive.</div> <div class="label mt-20">Articles</div> <ul class="list-unstyled"> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/conservation-ecology">conservation</a> <div class="font-serif">ecology</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/topic/Environmental-Protection-Agency">Environmental Protection Agency</a> <div class="font-serif">United States government agency</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/hydrosphere">hydrosphere</a> <div class="font-serif">Earth science</div> </li> </ul> </div> <div class="col-100 col-sm-33 col-md-25"> <a href="/browse/Mammals"> <img loading="lazy" src="https://cdn.britannica.com/03/155303-050-E2B63186/platypus-duckbill-waterways-Australia.jpg?w=400&h=225&c=crop" alt="platypus" class="col-100 mb-20" /> </a> <a href="/browse/Mammals" class="font-weight-bold font-16">Mammals</a> <div class="font-serif mt-10 line-clamp clamp-3">Mammals are distinguished by their ability to produce milk. The class Mammalia boasts tremendous diversity in form and habit, and different types of mammals can be wildly different from one another in physical appearance. Living kinds of mammals range in size from a bat weighing less than a gram to the largest animal that has ever lived, the blue whale, which reaches a length or more than 30 metres (100 feet) and a weight of 180 metric tons (nearly 200 short [U.S.] tons).</div> <div class="label mt-20">Articles</div> <ul class="list-unstyled"> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/armadillo-mammal">armadillo</a> <div class="font-serif">mammal</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/meerkat">meerkat</a> <div class="font-serif">mammal</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/animal/squirrel-monkey">squirrel monkey</a> <div class="font-serif">primate</div> </li> </ul> </div> <div class="col-100 col-sm-33 col-md-25"> <a href="/browse/Mathematics"> <img loading="lazy" src="https://cdn.britannica.com/mendel/resources/encyclopedia-placeholder.jpg?w=400&h=225&c=crop" alt="subcategory placeholder" class="col-100 mb-15" /> </a> <a href="/browse/Mathematics" class="font-weight-bold font-16">Mathematics</a> <div class="font-serif mt-10 line-clamp clamp-3">Mathematics is a science of structure, order, and relation that deals with logical reasoning and quantitative calculation. The history of mathematics can be traced back to ancient Mesopotamia; ancient clay tablets have proven that the level of mathematical competence was already high as early as roughly the 18th century BCE. Over the centuries, mathematics has evolved from elemental practices of counting, measuring, and describing the shapes of objects into a crucial adjunct to the physical sciences and technology.</div> <div class="label mt-20">Articles</div> <ul class="list-unstyled"> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/equation">equation</a> <div class="font-serif">mathematics</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/arithmetic">arithmetic</a> <div class="font-serif"></div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/algebra">algebra</a> <div class="font-serif">mathematics</div> </li> </ul> </div> <div class="col-100 col-sm-33 col-md-25"> <a href="/browse/Plants"> <img loading="lazy" src="https://cdn.britannica.com/66/166066-050-7EF755F4/flower-Rafflesia-arnoldii-plant-world-endoparasite-host.jpg?w=400&h=225&c=crop" alt="Rafflesia flower" class="col-100 mb-20" /> </a> <a href="/browse/Plants" class="font-weight-bold font-16">Plants</a> <div class="font-serif mt-10 line-clamp clamp-3">Life on Earth owes much to plants. The vast majority of plants carry out photosynthesis to transform light energy into chemical energy, which is the way that virtually all energy in the biosphere becomes available to living things (including us humans). Plants occupy the base of Earth's food webs and are consumed directly or indirectly by all higher life-forms, thereby functioning as the major source of food for humans and other animals. Plants' photosynthetic activity also produces the air that we breathe: almost all the oxygen in the atmosphere is due to the process of photosynthesis. Still not convinced about the merits of plants? Consider the fact that many plants not only serve up crucial nutrients and breathable air but also look good doing it. Many plants are admired for their striking aesthetic qualities, and flowers such as tulips, lilies, sunflowers, and daisies beautify fields, gardens, windowsills, and bouquets the world over. Plants are also a primary source of consumer goods, such as building materials, textile fibers, and pharmaceuticals.</div> <div class="label mt-20">Articles</div> <ul class="list-unstyled"> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/plant/plant">plant</a> <div class="font-serif">organism</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/houseplant">houseplant</a> <div class="font-serif">plant</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/plant/fern">fern</a> <div class="font-serif">plant</div> </li> </ul> </div> <div class="col-100 col-sm-33 col-md-25"> <a href="/browse/Physics"> <img loading="lazy" src="https://cdn.britannica.com/34/1534-004-5BBDA0CA/diagram-flotation-separation-cell.jpg?w=400&h=225&c=crop" alt="Schematic diagram of a flotation separation cell." class="col-100 mb-20" /> </a> <a href="/browse/Physics" class="font-weight-bold font-16">Physics</a> <div class="font-serif mt-10 line-clamp clamp-3">What鈥檚 the matter? Matter is the material substance that constitutes our whole observable universe, and it is the subject of study of physics. Physics, the basic physical science, studies objects ranging from the very small (using quantum mechanics) to the entire universe (using general relativity). It deals with the structure of matter and how the fundamental constituents of the universe interact.</div> <div class="label mt-20">Articles</div> <ul class="list-unstyled"> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/principles-of-physical-science">principles of physical science</a> <div class="font-serif"></div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/fluid-mechanics">fluid mechanics</a> <div class="font-serif">physics</div> </li> <li class="mt-20"> <a class="font-weight-bold" href="https://www.britannica.com/science/gravity-physics">gravity</a> <div class="font-serif">physics</div> </li> </ul> </div> </div> <DIV class="marketing-CATEGORY_PAGE_SUBSCRIPTION marketing-content" data-marketing-id="CATEGORY_PAGE_SUBSCRIPTION"><style> .student-promo-banner-wrapper { container-type: inline-size; margin-bottom: 15px; } @container (min-width: 475px) { .student-promo-banner { flex-direction: row; } .student-promo-banner-img-wrapper { margin-bottom: 0; margin-right: 10px; justify-content: flex-start; } .student-promo-banner-text-wrapper { text-align: left; margin-bottom: 0px; margin-left: 10px; } .student-promo-banner-button-wrapper { margin-right: 0; } }</style> <div class="student-promo-banner-wrapper"> <div class="student-promo-banner d-flex flex-column align-items-center bg-blue rounded p-20"> <div class="student-promo-banner-img-wrapper mb-20 mr-0 d-flex justify-content-center"> <img class="rounded" style="max-width: 100px; min-width: 80px" src="https://cdn.britannica.com/marketing/BlueThistle.webp" /> </div> <div class="student-promo-banner-text-wrapper ml-0 mb-10 text-center text-white"> <div class="h2 mb-10">Britannica Premium</div> <div class="h4 font-weight-semi-bold">Did you know you're not getting the full Britannica experience? 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