An apartment (in American English) or a flat (in British English) is a self-contained housing unit (a type of residential real estate) that occupies only part of a building. Such a building may be called an "apartment building", "apartment house" (in American English), "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's 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).