Generally, a periphery is a boundary or outer part of any space or body. It is derived from the Greek word περιφέρεια, meaning a circumference or outer surface.

• In biology, the periphery of the body is the part that is away from the central or core regions.
  • For example, the peripheral nervous system is distinct from the central nervous system.
  • See also peripheral membrane protein.

• Peripheral vision is that part of visual perception that occurs in the periphery, i.e., near the edges, of the field of view.

• In computer hardware, a peripheral is added to a host computer in order to expand its abilities. This is not to be confused with a peripheral device.

• For peripheral submanifolds in mathematics, see boundary parallel.

• The Periphery includes nations that are not "core" capitalist or industrialized nations. See Immanuel Wallerstein, Third World.

• The 13 peripheries of Greece are subnational subdivisions of that country.

• In BattleTech game, the Periphery is the region filled with less developed space colonies, most distant from Earth.