A continent (from the Latin "continere" for "to hold together") is a large continuous mass of land in the planet Earth.

Physical map of the world.

There is no single standard for what defines a continent, and therefore various cultures and sciences have different lists of what are considered to be continents. In general, a continent must be large in area, consist of non-submerged land, and have geologically significant borders. While some consider that there are as few as four or five continents, the most commonly used counts are six or seven.

Two of the largest disagreements in listing continents are whether Europe and Asia should be considered separately or combined into Eurasia, and whether North America and South America should be considered separately or combined into America. A few geographers have also suggested grouping Europe, Asia, and Africa into a continent of Eurafrasia (see Africa-Eurasia).

The seven continent model is commonly taught in Western Europe and North America, while the six continent (combined Eurasia) model is also taught in North America and is the primary continent model used in scientific contexts. The six continent (combined Americas) model is commonly taught in Eastern Europe and South America.

Continents are sometimes conceptually combined to make "supercontinents" or subdivided to make "subcontinents". These terms are less precisely defined than "continent" itself.

Islands are usually considered to "belong" to the continent they are closest to, and hence the British Isles are considered to be a part of Europe. Sometimes Australasia or "Oceania" is used to refer collectively to Australia and the Pacific islands. Both terms, however, have fairly precise meanings.

When "The Continent" is referred to without clarification by a speaker of British English, it is usually presumed to mean Europe. Similarly, when the term "the Subcontinent" is used, it is presumed to refer to India.

See also List of countries by continent, Satellite Images of Continents.

Some systems of defining continents

Seven Continents: Africa, Antarctica, Asia, Australia (Oceania), Europe, North America, and South America.
Six Continents: Africa, Antarctica, Australia (Oceania), Eurasia, North America, and South America.
Six Continents: Africa, America, Antarctica, Asia, Australia (Oceania), and Europe.
Five Continents: Asia, Africa, America, Oceania, Antarctica.
Five Continents: Eurasia, Africa, America, Australia (Oceania), Antarctica.
Four Continents: Eurafrasia, America, Australia (Oceania), Antarctica

See also: continental shelf, earth science, geography, geology, plate tectonics.