|An apartment 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).
A common alternative term for apartment is 'flat'. The term "apartment" is favored in North America, whereas the term "flat" is commonly, but not exclusively, used in the United Kingdom, Ireland and the Commonwealth nations. In Malaysian English, "flat" often denotes a housing block of lesser quality meant for lower-income groups, while "apartment" is more generic and may also include luxury condominiums.
Some apartment-dwellers own their own 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. The word apartment connotes a residential unit or section in a building. In some locations, particularly the United States, the word denotes a rental unit owned by the building owner, and is not typically used for a condominium.
The word unit is a more general term referring to both apartments and rental business suites. The word is generally used only in the context of a specific building. E.g., "This building has three units" or "I'm going to rent a unit in this building", but not "I'm going to rent a unit somewhere."
Upmarket apartments in Bristol, England
When there is no tenant occupying an apartment, the lessor is said to have a vacancy. For apartment lessors, each vacancy represents a loss of income from rent-paying tenants for the time the apartment is vacant (i.e., unoccupied). Lessors' objectives are often to minimize the vacancy rate for their units. The owner of the apartment, typically when transferring possession to the occupant, gives him/her the key to the apartment entrance and any other keys needed, such as a common key to the building or any other common areas and a mailbox key. When the occupant(s) move out, these keys are typically returned to the owner.