A housing unit, or dwelling unit, (at later mention often abbreviated to unit) is a structure or the part of a structure or the space that is used as a home, residence, or sleeping place by one person or more people who maintain a common household.
In common speech in Australia and New Zealand, the word "unit", when referring to housing, usually means an apartment, where a group of apartments is contained in one or more multi-storey buildings (an 'apartment block'), or a villa unit or home unit, where a group of dwellings is in one or more single-storey buildings, usually arranged around a driveway. Then, a unit is a self-contained suite of rooms, usually of modest scale, which may be attached, semi-detached or detached, within a group of similar dwellings. Used in the Australian and New Zealand urban planning and development industry, it is also a synonym for dwelling.
A single room unit is more commonly referred to as a studio flat or bedsitter, otherwise known as a Single Room Occupancy or SRO in North America. It can be hard to discern precisely what attributes distinguish some multi-dwelling developments as units from those referred to as flats or apartments, but everyday usage suggests there is a class dimension to the term.
In Canada, the national statistical agency, Statistics Canada, counts the number of private dwellings in the country at each census, in which case they are then known as "dwelling units" and can refer equally to a house or an apartment. In everyday Canadian English "unit" is used an umbrella term for apartments and condominiums.