A continent is one of the main land masses of Earth (or of a planet--on the hypothesis that there are other planets with oceans and land masses similar to the Earth's).
A land mass larger than a continent is called a supercontinent. The classification of land masses as continents, supercontinents and islands is by enumeration: the following land masses are declared to be continents:
Continents are often combined with nearby islands to form regions of the same name: e.g., the British Isles are placed with Europe.
The Pacific islands and Australia are sometimes combined as Oceania.