A townhouse, or town house, as used in North America, Asia, Australia, South Africa and parts of Europe, is a type of medium-density housing in cities, usually but not necessarily terraced (row housing) or semi-detached. A modern town house is often one with a small footprint on multiple floors. The term originally referred in British usage to the city residence of a member of the nobility, as opposed to their country seat.
Historically, a town house was the city residence of a noble or wealthy family, who would own one or more country houses in which they lived for much of the year. From the 18th century, landowners and their servants would move to a townhouse during the social season (when major balls took place).
In the United Kingdom most townhouses were terraced. Only a small minority of them, generally the largest, were detached, but even aristocrats whose country houses had grounds of hundreds or thousands of acres often lived in terraced houses in town. For example the Duke of Norfolk owned Arundel Castle in the country, while his London house, Norfolk House, was a terraced house in St. James’s Square over 100 feet (30 meters) wide.
Condominium townhouses, just like condominium apartments, are often referred to as “condos”, thus referring to the type of ownership rather than to the type of dwelling. Since apartment style condos are the most common, when someone refers to a “condo”, many erroneously assume that it must be an apartment style dwelling and conversely that only apartment style dwellings can be condos. All types of dwellings can be condos and this is therefore true of townhouses. A “Brownstone” townhouse is a particular variety found in New York.