Europe, 6th largest continent, c.4,000,000 sq mi (10,360,000 sq km) including adjacent islands (1992 est. pop. 512,000,000). It is actually a vast peninsula of the great Eurasian land mass. By convention, it is separated from Asia by the Urals and the Ural River in the east; by the Caspian Sea and the Caucasus in the southeast; and by the Black Sea, the Bosporus, the Sea of Marmara, and the Dardanelles in the south. The Mediterranean Sea and the Strait of Gibraltar separate it from Africa. Europe is washed in the north by the Arctic Ocean, and in the west by the Atlantic Ocean, with which the North Sea and the Baltic Sea are connected.
The Americas, or America, also known as the New World, are the combined continental landmasses of North America and South America,in the Western Hemisphere. Along with their associated islands, they cover 8.3% of the Earth’s total surface area (28.4% of its land area). The topography is dominated by the American Cordillera, a long chain of mountains that run the length of the west coast. The flatter eastern side of the Americas is dominated by large river basins, such as the Amazon, Mississippi, and La Plata. Since the Americas extend 14,000 km (8,700 mi) from north to south, the climate and ecology vary widely, from the arctic tundra of Northern Canada, Greenland, and Alaska, to the tropical rain forests in Central America and South America.
Africa, second largest continent (2009 est. pop. 1,010,000,000), c.11,677,240 sq mi (30,244,050 sq km) including adjacent islands. Broad to the north (c.4,600 mi/7,400 km wide), Africa straddles the equator and stretches c.5,000 mi (8,050 km) from Cape Blanc (Tunisia) in the north to Cape Agulhas (South Africa) in the south. It is connected with Asia by the Sinai Peninsula (from which it is separated by the Suez Canal) and is bounded on the N by the Mediterranean Sea, on the W and S by the Atlantic Ocean, and on the E and S by the Indian Ocean. The largest offshore island is Madagascar; other islands include St. Helena and Ascension in the S Atlantic Ocean; São Tomé, Príncipe, Annobón, and Bioko in the Gulf of Guinea; the Cape Verde, Canary, and Madeira islands in the N Atlantic Ocean; and Mauritius, Réunion, Zanzibar, Pemba, and the Comoros and Seychelles in the Indian Ocean.
Asia As the largest and most populous continent in the world with just over 3.8 billion people, Asia is composed of a wide variety of ethnic groups, cultures, environments, economics, historical ties, and governmental systems. Geographically the continent makes up 8.7% of the Earth’s total surface area, and 29.5% of its land area. In the west, Asia is bordered by Europe, the eastern coastline of the Mediterranean Sea, as well by the Sea of Marmara, the Bosporus Strait, the Black Sea and the Caspian Sea. In the east, Asia is bordered by the Pacific Ocean, and an almost endless stretch of bays and seas.
Australia is an island continent and the world’s sixth largest country (7,682,300 sq km). Lying between the Indian and Pacific oceans, the country is approximately 4,000 km from east to west and 3,200 km from north to south, with a coastline 36,735 km long. Canberra is Australia’s capital city. With a population of approximately 320,000 people and situated in the Australian Capital Territory, Canberra is roughly half way between the two largest cities Melbourne and Sydney. Australia has 19 listed World Heritage properties. Australia is also famous for its landmark buildings including the Sydney Harbour Bridge; its ancient geology, as well as for its high country.
Sources: http://www.encyclopedia.com/topic/Europe.aspx | http://en.wikipedia.org/wiki/Americas| http://www.encyclopedia.com/topic/Africa.aspx | http://www.worldatlas.com/webimage/countrys/as.htm | http://www.australia.gov.au/about-australia/our-country