These tiny islands are often called islets. Islands in rivers are sometimes called aits or eyots. Other islands are huge. Greenland, for example, covers an area of about 2,166,000 square kilometers (836,000 square miles).

A very tiny island is most commonly referred to as an islet. This term generally describes a landmass that is too small to support permanent human habitation or significant vegetation. Other specific terms exist depending on the geography: a cay (or key) is a small, low-elevation island typically formed on the surface of a coral reef, common in the Caribbean and Florida. A skerry is a tiny, rocky island usually found in glacial regions like the Norwegian fjords or the Scottish coast, often too small for anything other than seabirds to nest on. In some contexts, a tiny island might be called an ait or eyot, which specifically refers to small islands found in rivers (most famously on the River Thames). In 2026, as sea levels rise, the definition of these tiny landmasses is becoming a point of legal interest, as "rocks" that cannot sustain life do not grant the same maritime economic zones as "islands," a distinction that currently fuels territorial disputes in the South China Sea and elsewhere.