Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, the Cape sugarbird is found exclusively in southwestern South Africa and is therefore said to be endemic to that particular part of the world.

An endemic species can also be referred to as an endemism or in scientific literature as an endemite. For example Cytisus aeolicus is an endemite of the Italian flora. Adzharia renschi was once believed to be an endemite of the Caucasus, but it was later discovered to be a non-indigenous species from South America belonging to a different genus.Some endemics are restricted to very small ranges. Tahina spectabilis for example is native to only 12 acres (4.8 hectares) and the tiny waterlily Nymphaea thermarum was native to a single thermal mudhole in Ruwanda of a few square yards (a few square meters)

The extreme opposite of an endemic species is one with a cosmopolitan distribution, having a global or widespread range.

A rare alternative term for a species that is endemic is "precinctive", which applies to species (and other taxonomic levels) that are restricted to a defined geographical area. Other terms that sometimes are used interchangeably, but less often, include autochthonal, autochthonic, and indigenous, however, these terms do not reflect the status of a species that specifically belongs only to a determined place.