Science
How can the sky be blue one day and stormy the next? Why do heavy objects tend to fall downwards when dropped? How are birds able to fly (and why can’t 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.
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Featured content, November 05, 2025
nervous system
Nervous system, organized group of cells specialized for the conduction of electrochemical stimuli from sensory receptors...
radiation
Radiation, flow of atomic and subatomic particles and of waves, such as those that characterize heat rays, light rays, and...
mechanics
Mechanics, science concerned with the motion of bodies under the action of forces, including the special case in which a...
typology
Typology, system of groupings (such as “landed gentry” or “rain forests”), usually called types, the members of which are...
star
Star, any massive self-luminous celestial body of gas that shines by radiation derived from its internal energy sources....
metabolism
Metabolism, the sum of the chemical reactions that take place within each cell of a living organism and that provide energy...
Big Science
Big Science, style of scientific research developed during and after World War II that defined the organization and character...
scientific theory
Scientific theory, systematic ideational structure of broad scope that encompasses a family of empirical (experiential) laws...
Science Quizzes
27 True-or-False Questions from Britannica’s Most Difficult Science Quizzes
How much do you know about Mars? How about energy? Think it’ll be easier if you have to pick only true or false? Find out...
36 Questions from Britannica’s Most Popular Science Quizzes
How well do you know astronomy? How about quantum mechanics? This quiz will take you through 36 of the hardest questions...
39 of the Most Challenging World Capitals Across History
Paris, Bujumbura, Pierre, and Nuuk all have something in common: they are all capital cities. And there are thousands more....
41 Questions from Britannica’s Most Popular World History Quizzes
This quiz collects 41 of the toughest questions from Britannica’s most popular quizzes on world history. If you want to ace...
43 Questions About Politics (Mostly in the United States) Compiled from Britannica’s Quizzes
This quiz gathers together questions from Britannica’s quizzes about politics, law, and government. It includes a lot of...
44 Questions from Britannica’s Most Popular Health and Medicine Quizzes
How much do you know about human anatomy? How about medical conditions? The brain? You’ll need to know a lot to answer 44...
47 Questions from Britannica’s Most Popular Geography Quizzes
Only the best and most determined quizmasters should tackle this quiz. It consists of questions taken from Britannica’s most...
49 Questions from Britannica’s Most Popular Literature Quizzes
Literature is a broad term that—among Britannica’s quizzes, at least—can include everything from American novels...
50 Capital Cities at Random Quiz
How well do you know seats of power around the world? We’ll give you a capital, you name the country, state, province.
50 States, 50 Fun Facts Quiz
Find out something that makes each state great.
Science Videos
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Science Subcategories
AstronomyHuman beings have long been fascinated by the celestial sphere above, whose twinkling lights have inspired not only scientific theories but also many artistic endeavors. 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.
Articles
- solar systemastronomy
- Buzz AldrinAmerican astronaut
- Yuri GagarinSoviet cosmonaut
BiologyHow 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’s still out on what our appendixes are for). Biology’s diverse fields include botany, ecology, evolution, genetics, medicine, physiology, and zoology.
Articles
Birds, Reptiles & Other VertebratesAlthough 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).
Articles
- amphibiananimal
- chondrichthyanfish class
- fishanimal
Bugs, Mollusks & Other Invertebrates Yet, in addition to being critically important—because they naturally recycle decaying matter—in 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.
Articles
- nematodeanimal
- giant squidmollusk
- butterflyinsect
ChemistryHow 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.
Articles
- Frédéric and Irène Joliot-CurieFrench chemists
- noble gaschemical elements
- biogeochemistry
Earth Science, Geologic Time & FossilsPlanet 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’s crust, oceans, and atmosphere.
Articles
- meteorologyscience
- Gaia hypothesisEarth science
- climatologymeteorology
EnvironmentBiological diversity is key to a healthy ecosystem, whether it’s 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.
Articles
- hydrosphereEarth science
- environmentbiology
- recycling
MammalsMammals 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).
Articles
MathematicsMathematics 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.
Articles
- algebramathematics
- trigonometry
- fractalmathematics
PlantsLife 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.
Articles
- plantorganism
- houseplantplant
- fernplant
PhysicsWhat’s 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.
Articles
- soundphysics
- string theoryphysics
- electron microscopeinstrument

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