The continents move. They break apart slowly, through geologic time, and then crash together again, to re-form the legendary super-continents. Right now we are in the dispersed part of the cycle.
The last supercontinent was Pangaea, a single mass that curved around the ancient Tethys Sea. It broke apart into Gondwana and Laurasia about 250 million years ago. Those lost continents drifted apart too, into the six or seven continents of today. Considered geographically there are six continents: Eurasia, Africa, North and South America, Australia, and Antarctica. Considered politically, Eurasia is split into Asia and Europe, giving the world seven continents.
Africa is the home of humankind, where our species arose. It is the second largest continent, and the second most populous. About 925 million people live in Africa. They are still overcoming a difficult colonial legacy. The highest mountain is Mount Kilimanjaro in Tanzania; the lowest point is Lake Assal in Djibouti. The plant and animal life of Africa is as varied as the climate, ranging from the lions of the savannah through the primates of the tropical rain forests to the scorpions and sand vipers of the Sahara. Africa is the poorest continent, in terms of wealth per capita, and has yet to profit from her vast natural resources.
Geographically speaking, Europe is the most western peninsula of Eurasia. The boundary line between it and Asia runs through the water divide of the Ural Mountains, along the Ural River, and through the Caspian Sea. Politically, Europe is considered a separate continent. More than 731,000,000 people live in Europe, making it the world's third most populous continent. Mount Elbrus in Russia is Europe's highest point; its lowest point is Lemmefjord in Denmark or Prins Alexander Polder in the Netherlands. The dominant powers of the colonial era were from Europe, and they held sway until their colonial role passed to Russia and America with the world wars. That era is over, though Europe is still recognized as the home of western thought.
Asia is the largest continent, and the most populous. It supports over 4 billion humans, about 60% of the world's people. It holds the earth's highest point, Mount Everest, and also its lowest, The Dead Sea, on the border of Jordan and Israel. Its plant native life ranges from the almond tree to the lotus. The animal life of Asia is diverse indeed, ranging from the Snow Leopard of the Himalayas to the Ibex of Saudi Arabia. Its many cultures are similarly diverse.
Antarctica is actually a desert, although 98% covered in ice that averages at least a mile thick. It's the fifth largest continent, at 5.4 million square miles, and is contained almost completely inside the Antarctic Circle. It's the windiest continent as well as the driest, and though it's covered with the ice of centuries, snow almost never falls except along the coast. Seventy percent of the world's fresh water is locked in the ice of Antarctica. Animal life, apart from under a thousand transient scientists and support staff members, and tourists along the coasts, consists of penguins, fur seals and sea birds. Plant life is cold adapted, and consists mostly of lichen, moss, and algae. The highest point in Antarctica is the Vinson Massif, located about 750 miles from the South Pole. By treaty, military and commercial uses of Antarctica are prohibited, and the ecology is protected. Antarctica is preserved for research to benefit the whole world.
Australia is mostly desert, though there's a fertile area in the southeast, and tropical areas in the north. It is the world's smallest continent, slightly smaller than the United States. More than 20,600,000 people live in Australia, mostly along the eastern and southeastern coast. The highest point in Australia is Mount Kosciuszko, and the lowest is Lake Eyre. About two percent of the population is aborigine. Like the Native Americans, the aborigines suffer from a difficult history. The plant and animal life of Australia is very different from that of the rest of the world: this is the land of the kangaroo, the koala, and the duck-billed platypus. Eucalyptus is native to Australia. The continent is rich in mineral wealth, and a stable government has enabled Australia to develop a strong and successful economy. Australia does worry about climate change issues, such as increased drought and ecological degradation of the Great Barrier Reef.
South America holds the world's highest mountain range, its largest river, and its highest waterfall, Angel Falls. It is fourth in land area, and fifth in population. More than 371,000,000 people live in South America. The Laguna del Carbon in Argentina is the continent's lowest point, and Aconcagua, also in Argentina, is the highest point. South American animals include the famous llama of the Andes, and the piranha of the Amazon River. The Amazon rainforest holds at least one in ten of all known species in the world. Brazil is the largest and most populous country in South America, and has Portuguese for its official language, but most of the other countries are Spanish-speaking.
North America is the third largest continent in area, and the fourth largest in population. Its highest point is Mount McKinley, also called Denali, in Alaska, and its lowest point is Death Valley in California. Most geographers divide North America from South America at the border between Panama and Colombia. The principal languages of North America are French, Spanish and English, although many other languages are still used. Animal life ranges from the polar bear to the elusive ocelot. Boreal forests are found in the north, and deserts and tropical rainforests farther south.