continent

A continent is a large landmass defined by convention rather than a universal scientific standard. In common usage, continents are the Earth's principal landmasses that separate major oceans. The number of continents varies by convention: the seven commonly taught are Africa, Antarctica, Asia, Europe, North America, South America, and Australia. In some classifications, Australia is grouped with nearby Pacific islands into a broader Oceania, and Europe and Asia may be combined as Eurasia, reducing the count to six or five.

Boundaries between continents are not fixed and may reflect geographic, cultural, historical, and political considerations as well as geology. For example, the boundary between Europe and Asia follows historical and cultural lines rather than a strict physical barrier.

Geologically, continents are part of Earth's lithosphere and are composed of continental crust that is less dense than oceanic crust. They drift slowly on the semi-fluid mantle beneath, a process driven by plate tectonics. Over geologic time, continents have joined into supercontinents such as Rodinia and Pangaea, and are slowly moving; the current continents are part of several major and minor tectonic plates.

Continents underpin much of human geography and are used to categorize regions for education, politics, and cultural analysis. They host diverse climates, ecosystems, and populations, with wide variation in size, shape, and resources.