An apartment, or flat, is a self-contained housing unit that occupies only part of a building. Such a building may be called an apartment building, especially if it consists of many apartments for rent. Apartments may be owned by an owner/occupier or rented by tenants.
The term apartment is favored in North America, whereas the term flat is commonly, but not exclusively, used in the United Kingdom, Hong Kong and most Commonwealth countries. 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.
Tenement law refers to the feudal basis of permanent property such as land or rents. May be found combined as in "Messuage or Tenement" to encompass all the land, buildings and other assets of a property.
In the US, 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.
In the UK, some flat owners own a share in the company that owns the freehold of the building. This 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.