In North America, the word apartment is preferred (although in some cities flat is used for a unit that is part of a house containing two or three units, typically one to a floor. The definition of apartment is: a room or suite of rooms fitted especially with housekeeping facilities and usually leased as a dwelling. This term is more generally used in professional real estate and architectural communities in the United Kingdom, while the term flat is frequently, but not entirely, used for a single-level apartment (thus a 'flat' apartment).

The term "unit" is used in various countries to refer to both residences and rented business suites. Only in the context of a specific building is the term 'unit' applied.

Within the same structure, "mixed-use buildings" integrate business and residential functions. Businesses on the lower floors (typically retail on the street-facing ground floor and supporting underground levels) and residential units on the upper floors are indicative of mixed-use buildings.

Definition of Apartment

Apartment complexes have been around for millennia. Except for the apartments of the private houses, very wealthy or Domus had given way to communal dwellings or insula in early imperial times in the principal towns of the Roman Empire due to urban congestion.  Buildings of four stories were popular, with six, seven, or eight stories being built on occasion. Another sort of apartment occurred in Europe during the Middle Ages, consisting of a large home or mansion that was subdivided into smaller apartments to house an important person's servants and other retainers.

Unlike these "apartments," which were merely personal rooms within enormous mansions, the modern apartment house first developed in Paris and other major European cities in the 18th century, when tall blocks of flats for middle-class renters began to arise. The size of the flats (and the residents' financial means) reduced with each subsequent floor in a four- or five-story building in a typical Parisian apartment building.

By the mid-nineteenth century, significant numbers of low-cost apartment dwellings were being built in cities and towns across Europe and the United States to accommodate an influx of industrial workers. These structures were frequently filthy, poorly constructed, unclean, and claustrophobic. Apartments colloquially known as railroad flats were set end-to-end in a row like boxcars in the typical New York City apartment, or tenement, which was initially built in the 1830s. Indeed, before 1918, few low-cost apartment complexes in Europe or America were constructed for comfort or aesthetics.

However, in many European capitals, particularly in Paris and Vienna, the design of flats for the upper-middle class and the wealthy advanced dramatically in the second half of the nineteenth century.

Elevators, central heating, and other amenities that could be shared by a building's occupants were introduced in the early twentieth century, giving rise to the modern huge apartment complex. Apartments for the wealthy began to have additional features such as recreation areas, delivery and laundry services, as well as community dining rooms and gardens. As urbanization and growing land costs made single-family homes increasingly unaffordable in many areas, the multistory apartment house grew in importance.

Apartment complexes have become a popular kind of government-subsidized housing notably for the elderly,  people living in poverty areas, and working classes. In the Soviet Union and other countries where housing development was the duty of the state, apartment block towers were also developed in great numbers.

Evolution of Apartment Buildings

As a result of growing urbanization, the demand for apartment living has continued to rise since World War II. A mid- or high-rise apartment building has become a common sight in most major cities across the world, and the two- or three-story "walk-up" apartment remains popular in less densely populated locations.

The most typical way to live in an apartment house has been to rent it. Multiple ownership of units on a single site, on the other hand, has grown much more prevalent in the twentieth century. Cooperatives and condominiums are examples of such ownership. In a cooperative, all of the residents in a building share ownership of the structure; cooperative housing is far more widespread in Europe than in the United States. Where there are apartments, there are apartment associations, which can include investors, property managers, apartment owners, and residents, among others.

Condominiums are becoming increasingly popular in the United States and internationally, because, unlike cooperative members, condominium owners are not financially reliant and can mortgage their property.

By Housing Tenure

Some apartment dwellers in the United States own their units, either through a housing cooperative, in which residents hold shares in a corporation that owns the building or property, or through a condominium, in which people own their apartments and share ownership of the common areas.

The majority of apartments are in structures specifically constructed for them, however massive older houses are occasionally partitioned into apartments. A residential unit or segment of a building is referred to as an apartment. In some places, particularly in the United States, the term refers to a rental unit held by the building owner rather than a condominium.

Flat owners in England and Wales possess shares in the firm that owns the building's freehold while also leasing the flat. A "share of freehold" flat is what this deal is known as. Each flat owner in the building has the right to receive annual ground fees from the freehold business. The freeholder can also develop or sell the property, subject to any applicable planning and restrictions. In Scotland, where long leasehold residential property was once uncommon but is now impossible, this circumstance does not exist.

By Size of the Building

Apartment buildings are multi-story structures that include three or more residences in one structure. An apartment building, flat complex,  apartment complex, block of flats,  high-rise, tower block, or, occasionally, mansion block (in British English) may be named such a structure, especially if it contains several rental apartments. In Australia, a high-rise apartment building is known as an apartment tower, residential tower, or block of flats.

By Country

The difference between rental apartments and condominiums in American English is that, whereas rental buildings are held by a single company and rented out to a large number of people, condominiums are owned individually, but their owners still pay a monthly or yearly fee for building care. Condominiums are frequently leased as rental apartments by their owners.

A third option is a cooperative apartment complex (or "co-op"), which operates as a corporation with all tenants as shareholders. Cooperative building tenants do not own their apartments; instead, they possess a proportional number of shares in the cooperative as a whole. Cooperators pay a monthly fee for building maintenance, similar to condominiums. These buildings are popular in big cities like New York, and they're gaining popularity in other big cities across the country.

Although the word "flat" is often used in British English, property developers use the term "apartment" to refer to costly 'flats' in elite and expensive residential neighborhoods such as Belgravia and Hampstead in London. It's known as a block of flats in Scotland, or a tenement if it's a classic sandstone structure, a name that has a negative meaning elsewhere.

In India, the term "flat" refers to multi-story dwellings with elevators.

New Zealand English and Australian English have used the term flat in English for a long time (although it can refer to any rental property), and the terms unit or apartment have been used more recently. A 'unit' in Australia refers to a flat, an apartment, or even a semi-detached house.

The phrases "unit," "flat," and "apartment" are frequently interchanged in Australia. Because the term "flats" has a negative connotation, newer high-rise buildings are more commonly promoted as "apartments." Despite attempts by developers to sell it, the term condominium or condo is rarely used in Australia.

In Malaysian English, a flat is a two-bedroom apartment with a walk-up, no elevator, no utilities, typically five stories tall, and outside parking space, whereas an apartment is a more generic term that can include luxury condominiums.

The word apartment (apaato) is used for lower-income housing in Japanese English loanwords (Wasei-eigo), whereas mansions are used for high-end apartments; both names correspond to what English speakers consider an apartment. This use of the term mansion is similar to the British English term mansion block, which refers to prestigious Victorian and Edwardian furnished apartment complex with beautiful facades and big, high-ceilinged flats. Danchi is a Japanese word that refers to a big group of apartment buildings that are erected in a specific style and design, usually as government housing.

Types and Characteristics

Studio Apartment

In the United States and Canada, studio, efficiency, or bachelor apartments, as well as studio flats in the United Kingdom, are the smallest self-contained residences. These units often consist of a single large main room that serves as a living room, dining room, and bedroom, as well as kitchen amenities and a separate bathroom. A studio apartment is referred to as a "one-room" (wonroom) in Korea.

A bedsit is a British variation on single-room lodging, consisting of a bed-sitting room with a shared bathroom. It is not self-contained, and hence is not an apartment or flat in the sense of how the term is used in this article; it is part of what the UK government refers to as a House in Multiple Occupations.

Garden Apartment

In American English, Merriam-Webster describes a garden apartment as "a multiple-unit low-rise house with extensive grass or garden space." Apartment buildings are frequently constructed around courtyards with one end exposed to the open. A garden apartment shares certain traits with a townhouse: each apartment has its own building entryway, or shares that access with other apartments directly above and/or below it via a stairway and lobby.

Different from a townhouse, each apartment only has one story. Due to the lack of elevators, these garden apartment complexes are rarely more than three stories tall. The first "garden apartment" buildings in New York, USA, were five stories high and built in the early 1900s. Each apartment has a one-car garage and landscaped inner grounds are common.

Salon Apartment

The phrase "salon apartment" refers to the elite apartments erected as part of multi-family residences in Belgrade and other Yugoslav cities in the early twentieth century. These apartments were designed with a centrally situated anteroom that served as a dining room and one or more salon rooms. The majority of these apartments, as well as the earliest examples of apartments popularly known as 'salon apartments,' were erected in Belgrade (Serbia), with the notion of spatial and functional organization eventually spreading to other significant urban areas in Yugoslavia.


It differs from a flat in that it often has more than one story, with a staircase running from the entrance floor to the upper (or, in some circumstances, lower) floor within the home. This is a common arrangement in much post-war British housing (especially, but not solely, public housing), serving to save money by reducing the amount of space given to access corridors while also emulating the 'traditional' two-story terrace house to which many of the residents were accustomed. It also allows apartments to have windows on both sides of the residential building, even if they are entered via a corridor.

A maisonette could be made up of Tyneside flats, which are two-story terraces with pairs of single-story units. The use of two independent front doors onto the street, each leading to a single flat, is a distinguishing characteristic. The term "maisonette" could also refer to cottage flats, often known as "four-in-a-block apartments," which are popular in Scotland.

One Dwelling with Two Stories

The vast majority of residences are single-story, hence the term "flat." Some, like many residences, have two stories with internal stairs connecting them. As previously said, one term for this is "maisonette." Scissor section flats were used in some public and private housing in the United Kingdom. Penthouses may feature more than one story to emphasize the concept of luxury and space on a bigger scale. In certain nations, two-story dwellings are referred to as "townhouses" in new construction.

Loft Apartment

During the middle of the twentieth century, this form of apartment arose in North America. Originally, the phrase referred to a residential area established within a historic industrial structure, mainly from the nineteenth century. These big flats are linked to abandoned buildings in deteriorating portions of cities being occupied illegally by individual squatters and have found appeal among artists and musicians seeking accommodation in large cities (New York, for instance).

Furthermore, these loft flats were mainly found in old highrise warehouses and industries that had been abandoned due to changes in town planning and economic conditions in the mid-twentieth century. The resulting apartments created a whole new bohemian lifestyle and are set up in a completely different way than most urban living spaces, with workshops and art studio spaces frequently included. As the availability of eligible old buildings has dried up, developers have responded by erecting new structures in the same aesthetic.

A loft is a converted warehouse, industrial,  or commercial area into an apartment, but some modern lofts are created by design.

Serviced Apartment

This apartment is a residential space of any size that includes housekeeping and cleaning services given by the leasing agent on a regular basis. Serviced apartments, sometimes known as serviced flats, emerged in the early twentieth century and were briefly popular in the 1920s and 1930s. They're designed to blend the best aspects of luxury and self-contained flats, and they're frequently attached to a hotel.

Residents can take advantage of additional services such as housekeeping, catering,  laundry, and other services as needed, just like guests who are semi-permanently placed in a luxury hotel.

David is the co-founder & CMO of DoorLoop, a best-selling author, legal CLE speaker, and real estate investor. When he's not hanging with his three children, he's writing articles here!