In modern property law, individual ownership of one dwelling unit within a multidwelling building.
Unit owners have undivided ownership interest in the land and those portions of the building shared in common. This type of ownership has been present in Europe since the end of the Middle Ages; in the U.S. it dates to the latter half of the 19th century and has been popular in crowded urban areas. An alternative to the condominium is the cooperative, in which residents own a share of a corporation, with each share entitling the owner to reside in a particular unit in the building.