Under the widely taught seven continent model, Earth has seven continents called Asia, Africa, North America, South America, Antarctica, Europe and Australia. A continent is conventionally understood as one of Earth's major continuous or relatively distinct land areas, although there is no single universally accepted scientific definition that produces exactly seven continents in every geographical tradition. Asia is the largest continent by both area and population.
Africa is the second largest by area and contains the greatest number of sovereign countries under the conventional country counting system. North America and South America occupy much of the Western Hemisphere. Antarctica surrounds the South Pole and is almost entirely covered by ice. Europe is relatively small in physical area but has major historical, cultural and political significance. Australia is the smallest of the seven continents when Australia is treated as a continent rather than using the broader regional term Oceania.
Asia occupies most of the eastern part of the Eurasian landmass and extends from the Arctic region in the north to the Indian Ocean in the south and from the Middle East and Europe in the west to the Pacific Ocean in the east. It contains enormous geographical variation, including the world's highest mountains in the Himalayas, extensive deserts such as the Gobi and Arabian deserts, vast plains, tropical forests, tundra and major river systems.
Asia contains more than half of the world's human population and includes countries such as China, India, Japan, Indonesia, Saudi Arabia, Kazakhstan and Russia. Russia is geographically transcontinental because its territory lies in both Europe and Asia, while countries such as Turkey and Egypt also have territory on both sides of commonly recognised continental boundaries.
Africa lies primarily between the Atlantic Ocean to the west, the Indian Ocean to the east, the Mediterranean Sea to the north and the Southern Ocean region to the south. It is characterised by enormous ecological and geographical diversity, including the Sahara, the world's largest hot desert, the Congo Basin rainforest, the East African Rift, extensive savannas, highlands and major lakes such as Lake Victoria. Africa is crossed by the Equator and contains both northern and southern hemisphere environments.
The continent is conventionally divided into regions including Northern Africa, Western Africa, Central Africa, Eastern Africa and Southern Africa. Africa has played a central role in human evolution, and fossil evidence demonstrates that some of the earliest known members of the human lineage lived there.
North America includes Canada, the United States, Mexico, the countries of Central America and the island countries and territories of the Caribbean under the broad geographical definition of the continent. It extends from the Arctic regions in the north to the tropical environments around the Caribbean and Central America. Major physical features include the Rocky Mountains, Appalachian Mountains, Great Plains, Mississippi River system, Great Lakes, Canadian Arctic Archipelago, Mexican Plateau and large areas of tundra and boreal forest. Greenland is geographically part of North America even though it is politically associated with the Kingdom of Denmark. Central America is generally treated as a subregion of North America rather than as a separate continent in the seven continent model.
South America is connected to North America through the Isthmus of Panama and extends southward between the Pacific and Atlantic Oceans. Its major geographical features include the Andes, the Amazon Basin, the Amazon River, the Atacama Desert, the Brazilian Highlands and the Patagonian region. The Amazon rainforest is one of the world's largest tropical forest systems, while the Andes form the longest continental mountain range above sea level.
South America contains twelve sovereign states under the conventional count, although geographical definitions of its boundaries and the treatment of overseas territories can affect descriptions of political geography. Countries include Brazil, Argentina, Colombia, Peru, Chile, Bolivia and Ecuador. The continent contains environments ranging from equatorial rainforest to high mountain ecosystems, deserts, grasslands, temperate forests and subantarctic landscapes.
Antarctica is the southernmost continent and surrounds the geographic South Pole. It is the coldest, driest and windiest continent and has the highest average elevation of any continent because of its enormous ice sheet. Approximately 98 percent of the continent is covered by ice, although exposed rock and ice free areas occur in some locations. Antarctica has no permanent native human population and has no sovereign countries.
Its political status is governed through the Antarctic Treaty System, which regulates activities including scientific research and territorial claims. Antarctica is frequently divided into East Antarctica and West Antarctica by major geographical structures such as the Transantarctic Mountains and the West Antarctic Rift System. The continent is surrounded by the Southern Ocean under the five ocean model.
Europe occupies the western portion of the Eurasian landmass and is commonly separated from Asia by a conventional boundary involving the Ural Mountains, Ural River, Caspian Sea, Caucasus region, Black Sea and associated waterways, although the precise boundary has varied among geographical traditions. Europe includes the Iberian, Italian and Balkan peninsulas, the Scandinavian Peninsula, the British Isles and numerous smaller islands. It contains countries with highly varied physical geography, languages, political systems and historical traditions. The continent includes both densely populated urban regions and extensive forests, mountains, plains and northern tundra. Europe is often considered a separate continent primarily because of historical and cultural convention rather than because it is completely separated from Asia by an ocean.
Australia is the smallest continent in the seven continent model and consists geographically of the Australian mainland, Tasmania and associated islands depending on the particular geographical definition being used. The mainland contains deserts and semi arid landscapes across much of its interior, while more temperate and tropical environments occur around the coasts. Australia is also the name of a sovereign country occupying the continent and surrounding islands.
The term Oceania is broader than Australia as a continent because Oceania generally refers to a geographic region encompassing Australia, New Zealand, Melanesia, Micronesia and Polynesia and numerous Pacific islands. Consequently, statements about the smallest continent can appear different in sources that use Australia as a continent and sources that use Oceania as a broader continental or regional grouping.
