Earth's land is usually divided into seven continents: Asia, Africa, North America, South America, Antarctica, Europe and Australia. A continent is one of the large main divisions of land on Earth. Yet continents are defined by convention rather than by a strict rule, so people count them in different ways. The seven-continent model is the one most commonly taught in countries such as the United States, but it is a tradition as much as a measurement.

Other models draw the lines differently. Some people count only six continents by joining North America and South America into one called America, and another six-continent model joins Europe and Asia into one called Eurasia, mostly in Russia, Eastern Europe and Japan. The Olympic five-continent model leaves out Antarctica because it is uninhabited. The United Nations groups the world into five regions rather than seven continents: Asia, Africa, Europe (which includes Russia), the Americas and Oceania.

At Panama's narrowest part, North America is just 50 kilometers across, and the Isthmus of Panama joins it to South America. Europe and Asia have no sea between them at all, because they are really one huge piece of land, called Eurasia. Europe extends from the island nation of Iceland in the west to the Ural Mountains of Russia in the east, and the Urals run for approximately 2,500 kilometers.

Is there a way to define a continent by rock instead of by tradition? Geographers classify Australia as a continent because it sits on its own continental crust. Scientists theorize that continental material built up along the boundaries of tectonic plates through a process called subduction. In 2017 a team led by GNS Science proposed that Zealandia is a continent, although roughly 94 percent of it is underwater. The team argued that its isolation from Australia and its large area support the definition.

The Sahara makes up about 25 percent of Africa. Dunes, called ergs, cover only 20 percent of it, and gravel plains called regs cover 70 percent. There are over 90 oases in the Sahara. The Sahel is a belt that stretches roughly 5,400 kilometers across Africa, from Senegal to Sudan. Only 10 percent of the plants in the African rainforest have been identified.

Asia holds much of the world's high ground. The Himalaya extend for about 2,500 kilometers, and the Tibetan Plateau averages more than 4,500 meters above sea level. Approximately 2 billion people depend on the rivers fed by the plateau's glaciers. The Bay of Bengal, covering almost 2.2 million square kilometers, is the largest bay in the world. As of November 2026, the depth of Lake Baikal in southern Russia is given as 1,642 meters, the deepest lake in the world.

Europe has its own records. Europe's highest peak, Mount Elbrus at 5,642 meters, is in the Caucasus Mountains of Russia. Most of the Great European Plain lies below 152 meters in elevation. A fjord is a long, narrow inlet of the sea surrounded by high, rugged cliffs, and a peninsula is a piece of land surrounded by water on three sides. The Volga River drains Europe's largest watershed, about 1.38 million square kilometers.

North America has records of its own. The Rockies, North America's largest mountain chain, stretch from British Columbia, Canada, to the U.S. state of New Mexico. The Great Lakes form the planet's largest area of fresh water. The Caribbean region includes more than 7,000 islands, islets, reefs and cays. The tundra has permafrost, soil that is frozen for two or more years. The ice age that covered much of North America reached its peak about 18,000 years ago.

South America is a continent of extremes of water and height. Aconcagua, the highest peak in the Andes, stands at 6,962 meters. The Andes cover about 8,850 kilometers. NASA says the Amazon basin spans at least 6 million square kilometers, nearly twice the size of India, and National Geographic gives almost 7 million. The Amazon rainforest is home to one-fifth of the world's land species. The Orinoco River flows in a giant arc for more than 2,736 kilometers.

Antarctica is the windiest, driest and iciest place on Earth. Its ice sheet covers almost 14 million square kilometers. Together the Antarctic and Greenland ice sheets contain more than 99 percent of the land ice and over 68 percent of the fresh water on Earth. Scientists often discuss the Antarctic Ice Sheet as three regions: the East Antarctic Ice Sheet, the West Antarctic Ice Sheet and the Antarctic Peninsula. Antarctica is also the largest desert on Earth, covering 14.2 million square kilometers.

The country of Australia has a total area of 7,688,287 square kilometers, the world's sixth-largest. The Great Dividing Range, a long mountain range, rises near the east coast of Australia. The Great Barrier Reef off Queensland is approximately 2,300 kilometers long. Mainland Australia is known for the Outback, a desert area in the interior, and it is the flattest continent and the second-driest, after Antarctica.

The map has also moved. By 240 million years ago almost all of the world's land was joined in a single huge continent. Alfred Wegener proposed continental drift in the early 1900s, with three articles published in 1912, and it took several more decades for most scientists to accept it. North America and Europe are moving away from each other at about 2.5 centimeters per year, and the plates rest on the hot, molten rock of Earth's mantle.

Words to know

• convention: agreed habit
• subduction: sinking plate edge
• isthmus: narrow land bridge
• fjord: sea inlet
• peninsula: nearly surrounded land