A multi-family residence is a type of building that is intended for use by more than one family for residential purposes. Sometimes multi-family residences are called MDUs or multi-dwelling units.
Multi-family residences are a rather wide definition as they could refer to many different types of properties. It can range from 2 family duplexes to apartment towers that house dozens of families. Condominiums and semi-communal residences are also usually defined as multi-family residences. While townhouses tend to share walls with other buildings and residences, it is debatable whether they are multi-family residences and could be interpreted either way.
The city of Benson, Arizona for example, defines multi-family residences as the following:
Multi-family residence means any residential complex under single or corporate ownership, designed for use by more than one family unit; including apartments, mobile home parks, hotels, motels, school dormitories, guest ranches and churches, but excluding townhouses and condominium projects excepting those fixtures to which the public has general access such as restaurants, laundromats, bars, etc., and which shall be continued under the commercial classification.
There are many different types of multi-family residences. Their name can vary depending on the region and location of the property.
Multi-family residences are the most common type of home in large urban centers and cities. Single-family residences, on the other hand, tend to be more common in suburban and rural settings.
Historically some of the earliest forms of multi-family residences could be seen in ancient Rome. There are also the “Malice houses” of Madrid and the Casbah of Algiers which are other early examples of multi-family residences. These forms of residence were a rarity prior to the industrial revolution, even in large cities, however.