Population is a set of humans or other organisms in a given region or area. Governments conduct a census to quantify the resident population size within a given jurisdiction. The term is also applied to non-human animals, microorganisms, and plants, and has specific uses within such fields as ecology and genetics.

Etymology

The word population is derived from the Late Latin populatio (a people, a multitude), which itself is derived from the Latin word populus (a people).

Use of the term

Social sciences

In sociology and population geography, population refers to a group of human beings with some predefined feature in common, such as location, race, ethnicity, nationality, or religion.

Ecology

In ecology, a population is a group of organisms of the same species which inhabit the same geographical area and are capable of interbreeding. The area of a sexual population is the area where interbreeding is possible between any opposite-sex pair within the area and more probable than cross-breeding with individuals from other areas.

In humans, interbreeding is unrestricted by racial differences, as all humans belong to the same species of Homo sapiens.

In ecology, the population of a certain species in a certain area can be estimated using the Lincoln index to calculate the total population of an area based on the number of individuals observed.

Dynamics

Genetics

In genetics, a population is often defined as a set of organisms in which any pair of members can breed together.