world tree

Centre of the world, a widespread motif in myths and folktales among various peoples, especially in Asia, Australia, and North America. There are two main forms. In the vertical tradition, the tree extends between and connects earth, heaven, and the underworld; oracles, judgments, and other prophetic activities are performed at its base. In the horizontal tradition, the tree is planted at the centre of the world and is protected by supernatural guardians; it is the source of terrestrial fertility and life.

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Large merchant ship that visits designated ports on a regular schedule, carrying whatever cargo and passengers are available on the date of sailing. The first liners were operated in the North Atlantic, notably by Samuel Cunard of Britain, beginning in 1840. Their heyday lasted from the late 19th to the mid-20th century. Many were extraordinarily luxurious. Among the most famous were Cunarders such as the Mauretania and the Queen Mary; the German Vaterland (later renamed Leviathan), for many years the largest ship afloat; the ill-fated Titanic; and the United States. Their reign ended in the 1960s with the rise of jet travel, but liners ranging from cruise ships to refrigerated cargo ships continued to sail.

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Major surface currents of the world's oceans. Subsurface currents also move vast amounts of water, elipsis

Horizontal and vertical circulation system of ocean waters, produced by gravity, wind friction, and water density variation. Coriolis forces cause ocean currents to move clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere and deflect them about 45° from the wind direction. This movement creates distinctive currents called gyres. Major ocean currents include the Gulf Stream–North Atlantic–Norway Current in the Atlantic Ocean, the Peru (Humboldt) Current off South America, and the West Australia Current.

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Large, continuous body of salt water. Ocean covers nearly 71percnt of the Earth's surface and is divided into major oceans and smaller seas. The three principal oceans, the Pacific, Atlantic, and Indian, are largely delimited by land and submarine topographic boundaries. All are connected to what is sometimes called the Southern Ocean, the waters encircling Antarctica. Important marginal seas, primarily in the Northern Hemisphere, are partially enclosed by landmasses or island arcs. The largest are the Arctic Ocean and adjacent seas, Caribbean and adjacent waters, Mediterranean, Bering Sea, Sea of Okhotsk, Yellow and China Seas, and Sea of Japan.

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Body of salt water extending from the Antarctic region in the south to the Arctic circle in the north and lying between the continents of Asia and Australia on the west and North and South America on the east. It occupies about one-third of the surface of the earth and is by far the largest of the world's oceans. Its area, excluding adjacent seas, is approximately 63,800,000 sq mi (165,250,000 sq km), twice that of the Atlantic Ocean and more than the whole land area of the globe. Its mean depth is 14,040 ft (4,280 m). The western Pacific is noted for its many peripheral seas.

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Body of salt water stretching between Africa in the west, Australia in the east, Asia in the north, and Antarctica in the south. With an area of 28,360,000 sq mi (73,440,000 sq km), it covers approximately one-seventh of the Earth's surface, and it is the smallest of the world's three major oceans (see Atlantic Ocean; Pacific Ocean). Its greatest depth (24,442 ft [7,450 m]) is in the Java Trench. Its chief marginal seas include the Red Sea, Arabian Sea, Persian Gulf, Andaman Sea, Bay of Bengal, and the Great Australian Bight. Its major islands and island groups include Madagascar, Sri Lanka, and the Mascarenes.

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Ocean separating North and South America from Europe and Africa. The second largest of the world's oceans, the Atlantic has an area of 31,830,000 sq mi (82,440,000 sq km). With its marginal seas, including the Baltic, North, Black, and Mediterranean to the east, and Baffin Bay, Hudson Bay, the Gulf of St. Lawrence, Gulf of Mexico, and Caribbean Sea to the west, it covers some 41,100,000 sq mi (106,450,000 sq km). Including these latter bodies of water, its average depth is 10,925 ft (3,330 m); its maximum depth is 27,493 feet (8,380 m) in the Puerto Rico Trench. Its most powerful current is the Gulf Stream.

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Ocean centring approximately on the North Pole. Smallest of the world's oceans, it is almost completely surrounded by the landmasses of Eurasia and North America, and it is distinguished by a cover of ice. Lands in it and adjacent to it include Point Barrow in Alaska, the Arctic Archipelago, Greenland, Svalbard, Franz Josef Land, and northern Siberia. The ocean covers about 5,440,000 sq mi (14,090,000 sq km) and reaches a maximum depth of about 18,000 ft (5,500 m). Its marginal seas include the Barents, Beaufort, Chukchi, East Siberian, Greenland, Kara, Laptev, and White seas. Areas within the Arctic Circle were first explored beginning in the 9th century by the Norse. In the 16th–17th centuries explorers searching for the Northwest Passage reached the area; Martin Frobisher discovered the southern part of Baffin Island (1576–78), and Henry Hudson navigated the eastern coast of Hudson Bay (1610–11). Later explorers included Roald Amundsen, Fridtjof Nansen, Robert E. Peary, and Richard E. Byrd. Development of the area's natural resources was spurred by the discovery of oil in Alaska in the 1960s. Virtually all of the Arctic has now been mapped.

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Musical genre incorporating diverse styles from Africa, eastern Europe, Asia, South and Central America, the Caribbean, and nonmainstream Western folk sources. The term was first coined largely in response to the sudden increase of recordings in non-English languages that were released in Great Britain and the United States in the 1980s, but by the early 1990s world music had become a bona fide musical genre and counterpoint to the increasingly synthetic sounds of Western pop music. Initially, African popular music and world music were virtually synonymous, and the genre's biggest stars included the Nigerians King Sunny Ade and Fela Anikulapo Kuti and the Senegalese Youssou N'Dour. Moreover, one of its earliest advocates was the Cameroonian-born Frenchman Francis Bebey. By the 21st century world music encompassed everything from Pakistani singer Nusrat Fateh Ali Khan and the pop-flamenco of the French group the Gipsy Kings to “ambient-global” projects that merged so-called ethnic voice samples with state-of-the-art rhythm programming.

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Use of computer modeling and simulation to enable a person to interact with an artificial three-dimensional visual or other sensory environment. A computer-generated environment simulates reality by means of interactive devices that send and receive information and are worn as goggles, headsets, gloves, or body suits. The illusion of being in the created environment (telepresence) is accomplished by motion sensors that pick up the user's movements and adjust his or her view accordingly, usually in real time. The basis of the technology emerged in the 1960s in simulators that taught how to fly planes, drive tanks, shoot artillery, and generally perform in combat. It came of commercial age in the 1980s and is now used in games, exhibits, and aerospace simulators. It has potential for use in many fields, including entertainment, medicine and biotechnology, engineering, design, and marketing.

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or Web

Leading information-exchange service of the Internet. It was created by Tim Berners-Lee and his colleagues at CERN and introduced to the world in 1991. The Web gives users access to a vast array of documents that are connected to each other by means of hypertext or hyperlinks. A hypertext document with its corresponding text and hyperlinks is written in HTML and is assigned an on-line address, or URL. The Web operates within the Internet's basic client-server architecture. Individual HTML files with unique electronic addresses are called Web pages, and a collection of Web pages and related files (such as graphics files, scripted programs, and other resources) sharing a set of similar addresses (see domain name) is called a Web site. The main or introductory page of a Web site is usually called the site's home page. Users may access any page by typing in the appropriate address, search for pages related to a topic of interest by using a search engine, or move quickly between pages by clicking on hyperlinks incorporated into them. Though introduced in 1991, the Web did not become truly popular until the introduction of Mosaic, a browser with a graphical interface, in 1993. Subsequently, browsers produced by Netscape and Microsoft have become predominant.

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or Second World War

Ecstatic crowds in London celebrating the end of the European phase of World War II, May 8, 1945.

(1939–45) International conflict principally between the Axis Powers—Germany, Italy, and Japan—and the Allied Powers—France, Britain, the U.S., the Soviet Union, and China. Political and economic instability in Germany, combined with bitterness over its defeat in World War I and the harsh conditions of the Treaty of Versailles, allowed Adolf Hitler and the Nazi Party to rise to power. In the mid-1930s Hitler began secretly to rearm Germany, in violation of the treaty. He signed alliances with Italy and Japan to oppose the Soviet Union and intervened in the Spanish Civil War in the name of anticommunism. Capitalizing on the reluctance of other European powers to oppose him by force, he sent troops to occupy Austria in 1938 (see Anschluss) and to annex Czechoslovakia in 1939. After signing the German-Soviet Nonaggression Pact, Germany invaded Poland on Sept. 1, 1939. Two days later France and Britain declared war on Germany. Poland's defeat was followed by a period of military inactivity on the Western Front (see Phony War). At sea Germany conducted a damaging submarine campaign by U-boat against merchant shipping bound for Britain. By early 1940 the Soviet Union had divided Poland with Germany, occupied the Baltic states, and subdued Finland in the Russo-Finnish War. In April 1940 Germany overwhelmed Denmark and began its conquest of Norway. In May German forces swept through The Netherlands and Belgium on their blitzkrieg invasion of France, forcing it to capitulate in June and establish the Vichy France regime. Germany then launched massive bombing raids on Britain in preparation for a cross-Channel invasion, but, after losing the Battle of Britain, Hitler postponed the invasion indefinitely. By early 1941 Hungary, Romania, and Bulgaria had joined the Axis, and German troops quickly overran Yugoslavia and Greece in April. In June Hitler abandoned his pact with the Soviet Union and launched a massive surprise invasion of Russia, reaching the outskirts of Moscow before Soviet counterattacks and winter weather halted the advance. In East Asia Japan expanded its war with China and seized European colonial holdings. In December 1941 Japan attacked U.S. bases at Pearl Harbor and in the Philippines. The U.S. declared war on Japan, and the war became truly global when the other Axis Powers declared war on the U.S. Japan quickly invaded and occupied most of Southeast Asia, Burma, the Netherlands East Indies, and many Pacific islands. After the crucial U.S. naval victory at the Battle of Midway (1942), U.S. forces began to advance up the chains of islands toward Japan. In the North Africa Campaigns the British and Americans defeated Italian and German forces by 1943. The Allies then invaded Sicily and Italy, forcing the overthrow of the fascist government in July 1943, though fighting against the Germans continued in Italy until 1945. In the Soviet Union the Battle of Stalingrad (1943) marked the end of the German advance, and Soviet reinforcements in great numbers gradually pushed the German armies back. The massive Allied invasion of western Europe began with the Normandy Campaign in western France (1944), and the Allies' steady advance ended in the occupation of Germany in 1945. After Soviet troops pushed German forces out of the Soviet Union, they advanced into Poland, Czechoslovakia, Hungary, and Romania and had occupied the eastern third of Germany by the time the surrender of Germany was signed on May 8, 1945. In the Pacific an Allied invasion of the Philippines (1944) was followed by the successful Battle of Leyte Gulf and the costly Battles of Iwo Jima and Okinawa (1945). Atomic bombs were dropped on Hiroshima and Nagasaki in August 1945, and Japan's formal surrender on September 2 ended the war. Estimates of total military and civilian casualties varied from 35 million to 60 million killed, including about 6 million Jews who died in the Holocaust. Millions more civilians were wounded and made homeless throughout Europe and East Asia. Seealso Anti-Comintern Pact; Atlantic Charter; Battles of El Alamein, the Atlantic, the Bulge, Guadalcanal, and the Philippine Sea; Casablanca, Potsdam, Tehran, and Yalta conferences; Dunkirk Evacuation; lend-lease; Munich agreement; Nürnberg Trials; Siege of Leningrad; Sino-Japanese Wars; Omar Bradley, Winston Churchill, Dwight D. Eisenhower, Douglas MacArthur, Bernard Law Montgomery, Benito Mussolini, George Patton, Erwin Rommel, Franklin Roosevelt, Joseph Stalin, Yamamoto Isoroku, Georgy K. Zhukov.

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or First World War

(1914–18) International conflict between the Central Powers—Germany, Austria-Hungary, and Turkey—and the Allied Powers—mainly France, Britain, Russia, Italy, Japan, and (from 1917) the U.S. After a Serbian nationalist assassinated Archduke Francis Ferdinand of Austria in June 1914, a chain of threats and mobilizations resulted in a general war between the antagonists by mid-August. Prepared to fight a war on two fronts, based on the Schlieffen Plan, Germany first swept through neutral Belgium and invaded France. After the First Battle of the Marne (1914), the Allied defensive lines were stabilized in France, and a war of attrition began. Fought from lines of trenches and supported by modern artillery and machine guns, infantry assaults gained little ground and were enormously costly in human life, especially at the Battles of Verdun and the Somme (1916). On the Eastern Front, Russian forces initially drove deep into East Prussia and German Poland (1914) but were stopped by German and Austrian forces at the Battle of Tannenberg and forced back into Russia (1915). After several offensives, the Russian army failed to break through the German defensive lines. Russia's poor performance and enormous losses caused widespread domestic discontent that led to the Russian Revolution of 1917. Other fronts in the war included the Dardanelles Campaign, in which British and Dominion forces were unsuccessful against Turkey; the Caucasus and Iran (Persia), where Russia fought Turkey; Mesopotamia and Egypt, where British forces fought the Turks; and northern Italy, where Italian and Austrian troops fought the costly Battles of the Isonzo. At sea, the German and British fleets fought the inconclusive Battle of Jutland, and Germany's use of the submarine against neutral shipping eventually brought the U.S. into the war in 1917. Though Russia's armistice with Germany in December 1917 released German troops to fight on the Western Front, the Allies were reinforced by U.S. troops in early 1918. Germany's unsuccessful offensive in the Second Battle of the Marne was countered by the Allies' steady advance, which recovered most of France and Belgium by October 1918 and led to the November Armistice. Total casualties were estimated at 10 million dead, 21 million wounded, and 7.7 million missing or imprisoned. Seealso Battles of Caporetto and Ypres; Fourteen Points; Lusitania; Paris Peace Conference; Treaties of Brest-Litovsk, Neuilly, Saint-Germain, Sèvres, Trianon, and Versailles; Edmund H.H. Allenby, Ferdinand Foch, John French, Douglas Haig, Paul von Hindenburg, Joseph-Jacques-Césaire Joffre, Erich Ludendorff, John Pershing.

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International organization based in Geneva that supervises world trade. It was created in 1995 to replace the General Agreement on Tariffs and Trade (GATT). Like its predecessor, it aims to lower trade barriers and encourage multilateral trade. It monitors members' adherence to GATT agreements and negotiates and implements new agreements. Critics of the WTO, including many opponents of economic globalization, have charged that it undermines national sovereignty by promoting the interests of large multinational corporations and that the trade liberalization it encourages leads to environmental damage and declining living standards for low-skilled workers in developing countries. By the early 21st century, the WTO had more than 145 members.

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Complex formerly consisting of seven buildings around a central plaza, near the southern tip of Manhattan. Its huge twin towers (completed 1970–72) were designed by Minoru Yamasaki (1912–86). At 1,368 ft (417 m) and 1,362 ft (415 m) tall, they were the world's tallest buildings until surpassed in 1973 by the Sears Tower in Chicago. The towers were notable for the relationship of their simple, light embellishment to their underlying structure. In 1993 a bomb planted by terrorists exploded in the underground garage, killing several people and injuring some 1,000. A much more massive attack occurred on Sept. 11, 2001, when first One World Trade Center and then Two World Trade Center were struck by hijacked commercial airliners that were deliberately flown into them. Shortly thereafter both of the heavily damaged towers, as well as adjacent buildings, collapsed into enormous piles of debris. The attacks claimed the lives of some 2,750 people. Thousands more were injured. See September 11 attacks.

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Public-health agency of the UN, established in Geneva in 1948 to succeed two earlier agencies. Its mandate is to promote “the highest possible level of health” in all peoples. Its work falls into three categories. It provides a clearinghouse for information on the latest developments in disease and health care and establishes international sanitary standards and quarantine measures. It sponsors measures for the control of epidemic and endemic disease (including immunization campaigns and assistance in providing sources of pure water). Finally, it encourages the strengthening of public-health programs in member nations. Its greatest success to date has been the worldwide eradication of smallpox (1980).

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Major international football (soccer) competition. The tournament brings together 32 qualifying national teams from around the world, culminating in a match between the two top teams. It has been held every fourth year since 1930 (except during World War II). Followed and watched by billions of people worldwide, it has by far the greatest audience of any single sporting event in the world. Several competitions in other sports also use the name “world cup.”

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Christian ecumenical organization founded in 1948 in Amsterdam. It functions as a forum for Protestant and Eastern Orthodox denominations, which cooperate through the WCC on a variety of undertakings and explore doctrinal similarities and differences. It grew out of two post-World War I ecumenical efforts, the Life and Work Movement (which concentrated on practical activities) and the Faith and Order Movement (which focused on doctrinal issues and the possibility of reunion). The impetus for these two organizations sprang from the International Missionary Conference in Edinburgh in 1910, the first such cooperative effort since the Reformation. The Roman Catholic church, though not a member of the WCC, sends representatives to its conferences. The more fundamentalist Protestant denominations have also refused to join.

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Specialized agency of the United Nations system, established at the Bretton Woods Conference for postwar reconstruction. It is the principal international development institution. Its five divisions are the International Bank for Reconstruction and Development (IBRD; its main component), the International Development Association (IDA), the International Finance Corporation (IFC), the Multilateral Investment Guarantee Agency (MIGA), and the International Center for Settlement of Investment Disputes (ICSID). The IDA (founded 1960) makes interest-free loans to the bank's poorest member countries. The IFC (founded 1956) lends to private businesses in developing countries. The MIGA (founded 1985) supports national and private agencies that encourage foreign direct investment by offering insurance against noncommercial risks. The ICSID (founded 1966) was developed to relieve the IBRD of the burden of settling investment disputes. Seealso International Monetary Fund.

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Former U.S. airline acquired by the AMR Corp. Formed in 1930 as Transcontinental & Western Air, Inc., from two smaller airlines, the company established the first coast-to-coast service that same year, flying from Newark, N.J., to Los Angeles in 36 hours. In 1946 TWA began flights between New York City and Paris, and it expanded by the 1950s to routes through Europe, the Middle East, Africa, and Asia. It adopted its present name in 1950. Howard R. Hughes was its principal stockholder and guiding genius from 1939 to 1960–61, when he lost control to a group of investors. Financially troubled since the 1980s, TWA continued to operate despite twice landing in bankruptcy court in the 1990s. It was acquired by AMR, the parent company of American Airlines, in 2001.

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Former U.S. airline acquired by the AMR Corp. Formed in 1930 as Transcontinental & Western Air, Inc., from two smaller airlines, the company established the first coast-to-coast service that same year, flying from Newark, N.J., to Los Angeles in 36 hours. In 1946 TWA began flights between New York City and Paris, and it expanded by the 1950s to routes through Europe, the Middle East, Africa, and Asia. It adopted its present name in 1950. Howard R. Hughes was its principal stockholder and guiding genius from 1939 to 1960–61, when he lost control to a group of investors. Financially troubled since the 1980s, TWA continued to operate despite twice landing in bankruptcy court in the 1990s. It was acquired by AMR, the parent company of American Airlines, in 2001.

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Preeminent architectural and sculptural achievements of antiquity, as listed by various Greco-Roman observers. Included on the best-known list were the Pyramids of Giza (the oldest of the wonders and the only one substantially in existence today), the Hanging Gardens of Babylon (thought to be a series of landscaped terraces, ascribed to King Nebuchadrezzar II, the semilegendary Queen Sammu-ramat, or the Assyrian king Sennacherib), the Statue of Zeus at Olympia (a large gold-and-ivory figure of the god on his throne by Phidias), the Temple of Artemis at Ephesus (a temple, built in 356 BC, famous for its imposing size and the works of art that adorned it), the Mausoleum of Halicarnassus, the Colossus of Rhodes, and the Pharos of Alexandria (a lighthouse built circa 280 BC on the island of Pharos off Alexandria, said to have been more than 350 ft, or 110 m, high). These wonders inspired the compilation of many other lists of seven attractions, or “wonders,” by later generations.

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Series of international meetings of eminent scientists to discuss problems of nuclear weapons and world security. The first meeting was held in 1957 at the estate of Cyrus Eaton in Pugwash, Nova Scotia. The Pugwash organization was established to convene subsequent conferences to discuss arms control and disarmament; these were held in the Soviet Union, Britain, India, and the U.S., among other countries. The organization and its president and founding member, Joseph Rotblat (born 1908), received the 1995 Nobel Prize for Peace.

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known as the Wobblies

Radical labour organization founded in Chicago in 1905. The founders, who opposed the moderate policies of the AFL (see AFL-CIO), included William Haywood of the Western Federation of Miners, Daniel De Leon of the Socialist Labor Party, and Eugene V. Debs. In 1908 the IWW split, and a militant group led by Haywood prevailed. To reach its goal of worker control of the means of production, it advocated general strikes, boycotts, and sabotage. Its tactics led to arrests and adverse publicity, though it made gains through strikes in the mining and lumber industries. It opposed U.S. participation in World War I, and some of its leaders were prosecuted. By the 1920s membership had dwindled greatly.

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"The world" is a proper noun for the planet Earth envisioned from an anthropocentric or human worldview, as a place inhabited by human beings and other terrestrial lifes. It is often used to signify the sum of human experience and history, or the 'human condition' in general. The world population is approximately 6.68 billion people.

In a metaphysical context, World may refer to everything that constitutes reality and the Universe: see World (philosophy).


In English, world may be parsed as rooted in a compound of the obsolete words were, "man", and eld, "age"; thus, its etymology may be semantically rendered as "age or life of man". Compare to the word for "world" in a closely related language to English, Dutch, which is "wereld.


'World' distinguishes the entire planet or population from any particular country or region: world affairs are those which pertain not just to one place but to the whole world, and world history is a field of history which examines events from a global (rather than a national or a regional) perspective. Earth, on the other hand, refers to the planet as a physical entity, and distinguishes it from other planets and physical objects.

'World' can also be used attributively, as an adjective, to mean 'global', 'relating to the whole world', forming usages such as World community. See World (adjective).

By extension, a 'world' may refer to any planet or heavenly body, especially when it is thought of as inhabited.

'World', when qualified, can also refer to a particular domain of human experience.


Earth is the only place in the universe where life is known by humanity to exist at this time. Scientific evidence indicates that the planet formed 4.54 billion years ago, and life appeared on its surface within a billion years. Since then, Earth's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks harmful radiation, permitting life on land.

Earth's outer surface is divided into several rigid segments, or tectonic plates, that gradually migrate across the surface over periods of many millions of years. About 71% of the surface is covered with salt-water oceans, the remainder consisting of continents and islands; liquid water, necessary for all known life, is not known to exist on any other planet's surface. Earth's interior remains active, with a thick layer of relatively solid mantle, a liquid outer core that generates a magnetic field, and a solid iron inner core.

The earth consists of seven continents listed as follows: North America, South America, Antarctica, Africa, Europe, Asia and Australia; the largest of which is Asia. There are several other methods of determining the continents.

Earth is impacted upon by other objects in outer space, including the Sun and the Moon. At present, Earth orbits the Sun once for every roughly 365.26 times it rotates about its axis. This length of time is a sidereal year, which is equal to 365.26 solar days. The Earth's axis of rotation is tilted 23.4° away from the perpendicular to its orbital plane, producing seasonal variations on the planet's surface with a period of one tropical year (365.24 solar days). Earth's only known natural satellite, the Moon, which began orbiting it about 4.53 billion years ago, provides ocean tides, stabilizes the axial tilt and gradually slows the planet's rotation. A cometary bombardment during the early history of the planet played a role in the formation of the oceans. Later, asteroid impacts caused significant changes to the surface environment.


Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens. Compared to other species, humans have a highly developed brain capable of abstract reasoning, language, and introspection. This mental capability, combined with an erect body carriage that frees their upper limbs for manipulating objects, has allowed humans to make far greater use of tools than any other species. DNA evidence indicates that modern humans originated in Africa about 200,000 years ago. Humans now inhabit every continent and low Earth orbit, with a total population of over 6.68 billion humans as of March 2008.

Like most primates, humans are social by nature. However, humans are particularly adept at utilizing systems of communication for self-expression, the exchange of ideas, and organization. Humans create complex social structures composed of many cooperating and competing groups, from families to nations. Social interactions between humans have established an extremely wide variety of traditions, rituals, ethics, values, social norms, and laws which form the basis of human society. Humans have a marked appreciation for beauty and aesthetics which, combined with the human desire for self-expression, has led to cultural innovations such as art, literature and music.

Humans are noted for their desire to understand and influence the world around them, seeking to explain and manipulate natural phenomena through science, philosophy, mythology and religion. This natural curiosity has led to the development of advanced tools and skills; humans are the only extant species known to build fires, cook their food, clothe themselves, and use numerous other technologies.


A summary of world development:

See also

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