An apartment (or flat) is a self-contained housing unit that occupies only part of a building. Apartments may be owned (by an owner-occupier) or rented (by "tenants").
Some apartment-dwellers own their apartments, either as co-ops, in which the residents own shares of a corporation that owns the building, or development; or in condominiums, whose residents own their apartments and share ownership of the public spaces. Most apartments are in buildings designed for the purpose, but large older houses are sometimes divided into apartments.
In some parts of the world, the word apartment is used generally to refer to a new purpose-built self-contained residential unit in a building, whereas the word flat means a converted self-contained unit in an older building.
See also