By convention, the seven continents of the world are Asia, South America, Europe, North America, Australia, Antarctica and Africa. However, some geographers use different models that divide the world into six, five and four continents.
The earth's surface encompasses approximately 29 percent land and 71 percent water. Massive continuous expanses of landmasses called continents, mainly comprise dry land. These continents are completely enclosed by the major oceans that make up the planet's water.
Asia, which is the largest among the seven generally accepted continents, covers a total area of around 16,920,000 square miles. Along with Oceania, Asia is separated from the North and South American continents by the Pacific Ocean. The Indian Ocean also forms part of the southern portion of the continent. Africa comes after Asia in terms of land area, followed by North America, South America, Antarctica and Europe. Australia is considered to be the smallest continent, with an area of approximately 3,478,200 square miles. The Atlantic Ocean disconnects Europe, Asia and Africa from North and South America, while the Indian Ocean separates Australia and Africa. The Southern Ocean surrounds Antarctica, while the Arctic Ocean borders Europe, North America and Asia.
Other continent models consider Europe and Asia as one continent, commonly referred to as Eurasia. North America and South America are also sometimes designated as the Americas. Another model groups Africa, Europe and Asia into one continent called Afro-Eurasia. Other forms of continents include supercontinents, microcontinents, subcontinents and underwater continents.