Generally, a periphery is a boundary or outer part of any space or body.

In biology

• Peripheral nervous system, distinct from the central nervous system
• Peripheral membrane protein, proteins that temporarily adhere to the biological membrane with which they are associated
• Peripheral vision, part of visual perception that occurs near the edges of the field of view

In national divisions

• Periphery countries includes nations that are not core countries - capitalist or industrialized nations
• Peripheries of Greece, the 13 subnational subdivisions of that country, equivalent to regions
• The suburbs of a town or city

In fiction

• Periphery (BattleTech), the region of interstellar space in the fictional universe of BattleTech
• The Periphery, that part of the Empire that lies on the very edge of the Milky Way Galaxy in Issac Asimov's Foundation series

In other uses

• Peripheral, a device added to a host computer in order to expand its abilities
• Boundary parallel, a property of a mathematical submanifolds