Africa is the world's second-largest and second-most-populous continent. At about 30.2 million km2 (11.7 million sq mi) including adjacent islands, it covers six percent of Earth's total surface area and 20.4 percent of its total land area. With 1.1 billion people as of 2013, it accounts for about 15% of the world's human population.
Asia is the Earth's largest and most populous continent, located primarily in the eastern and northern hemispheres. Though it covers only 8.7% of the Earth's total surface area, it comprises 30% of Earth's land area, and has historically been home to the bulk of the planet's human population (currently roughly 60%).
Europe is the world's second-smallest continent by surface area, covering about 10,180,000 square kilometres (3,930,000 sq mi) or 2% of the Earth's surface and about 6.8% of its land area. Of Europe's approximately 50 countries, Russia is by far the largest by both area and population, taking up 40% of the continent (although the country has territory in both Europe and Asia), while Vatican City is the smallest. Europe is the third-most populous continent after Asia and Africa, with a population of 739–743 million or about 11% of the world's population. The most commonly used currency is the euro.
South America has an area of 17,840,000 square kilometers (6,890,000 sq mi). Its population as of 2005 has been estimated at more than 371,090,000. South America ranks fourth in area (after Asia, Africa, and North America) and fifth in population (after Asia, Africa, Europe, and North America).
North America covers an area of about 24,709,000 square kilometers (9,540,000 square miles), about 4.8% of the planet's surface or about 16.5% of its land area. As of 2013, its population was estimated at nearly 565 million people across 23 independent states, representing about 7.5% of the human population. Most of the continent's land area is dominated by Canada, the United States, Greenland, and Mexico, while smaller states exist in the Central American and Caribbean regions. North America is the third largest continent by area, following Asia and Africa, and the fourth by population after Asia, Africa, and Europe.
Antarctica is Earth's southernmost continent, containing the geographic South Pole. It is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14.0 million km2 (5.4 million sq mi), it is the fifth-largest continent in area after Asia, Africa, North America, and South America. For comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 kilometres (1.2 mi) in thickness, which extends to all but the northernmost reaches of the Antarctic Peninsula.
With a total land area of 8,560,000 square kilometres (3,310,000 sq mi), the Australian continent is the smallest and lowest-lying human-inhabited continent on Earth. The continental shelf connecting the islands, half of which is less than 50 metres (160 ft) deep, covers some 2,500,000 square kilometres (970,000 sq mi), including the Sahul Shelf and Bass Strait. As the country of Australia is mostly on a single landmass, and comprises most of the continent, it is sometimes informally referred to as an island continent, surrounded by oceans.