An apartment (American English), flat (British English) or unit (Australian English), is a self-contained housing unit (a type of residential real estate) that occupies only part of a building, generally on a single level.
Such a building may be called an apartment building, apartment complex, flat complex, block of flats, tower block, high-rise or, occasionally mansion block (in British English), especially if it consists of many apartments for rent. In Scotland, it is called a block of flats or, if it is a traditional sandstone building, a tenement, which has a pejorative connotation elsewhere. Apartments may be owned by an owner/occupier, by leasehold tenure or rented by tenants (two types of housing tenure).
Tenement law refers to the feudal basis of permanent property such as land or rents. It may be found combined as in "Messuage or Tenement" to encompass all the land, buildings and other assets of a property.
In the United States, some apartment-dwellers own their units, 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 denotes a residential unit or section in a building. In some locations, particularly the United States, the word connotes a rental unit owned by the building owner, and is not typically used for a condominium.
In South Africa An apartment is usually a single level rental area that is a part of a larger building and can be entered from inside the building through a separate door leading off either a wind tunnel or entrance hall/lobby that is shared with other occupants of the house or building. An apartment is in a building or converted house in which no space or single unit occupies an entire floor on its own. An apartment is like a subdivision of something bigger. Apartments are able be defined by their readiness to be rented to the greater public or holiday makers.
In the England and Wales, some flat owners own shares in the company that owns the freehold of the building as well as holding the flat under a lease. This arrangement is commonly known as a "share of freehold" flat. The freehold company has the right to collect annual ground rents from each of the flat owners in the building. The freeholder can also develop or sell the building, subject to the usual planning and restrictions that might apply. This situation does not happen in Scotland, where long leasehold of residential property was formerly unusual, and is now impossible.
In some countries the word "unit" is a more general term referring to both apartments and rental business suites. The word 'unit' 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". In Australia, a 'unit' refers to flats, apartments or even semi-detached houses. Some buildings can be characterized as 'mixed use buildings', meaning part of the building is for commercial, business, or office use, usually on the first floor or first couple of floors, and one or more apartments are found in the rest of the building, usually on the upper floors.