Population

In sociology and biology a population is the collection of people or organisms of a particular species living in a given geographic area or space, usually measured by a census.

Populations are studied, in particular, in a branch of ecology known as population biology, and in population genetics. In population dynamics, size, age and sex structure, mortality, reproductive behaviour, and growth of a population are studied. In biology, an isolated population denotes a breeding group whose members breed mostly or solely among themselves, usually as a result of physical isolation, although biologically they could breed with any members of the species. If there are several completely or nearly completely isolated populations in the global population of a taxon, these are called subpopulations. The metapopulation is a network of subpopulations in a given area (which may be global), where the individuals of the various subpopulations are able to cross uninhabitable areas of the region. Biological dispersal is one of the key elements affecting such populations; if dispersal is sufficiently low for a prolonged period of time, speciation is likely to be a consequence.

Demography is the study of human populations. Its three central foci are the processes of fertility, mortality, and migration, though the field encompasses many dimensions of population change including the family (marriage and divorce), public health, work and the labor force, and family planning. Various aspects of human behavior in populations are also studied in sociology, economics, and geography. Study of populations is almost always governed by the laws of probability, and the conclusions of the studies may thus not always be applicable to some individuals. This odd factor may be reduced by statistical means, but such a generalization may be too vague to imply anything. Demography is used extensively in marketing, which relates to economic units, such as retailers, to potential customers. For example, a coffee shop that wants to sell to a younger audience, looks at the demographics of an area to be able to appeal to this younger audience.