Suburbs are commonly defined as smaller residential communities lying immediately outside a city. In the United States, suburbs have a prevalence of usually detached single-family homes. Some suburbs have a degree of political autonomy, and most have lower population density than inner city neighborhoods. Modern suburbs grew in the 20th century as a result of improved road and rail transport and an increase in commuting. Suburbs tend to proliferate around cities which ideally have an abundance of adjacent flat land. Any particular suburban area is referred to as a suburb, while suburban areas on the whole are referred to as the suburbs or suburbia, with the demonym being a suburbanite.

Etymology and usage

The word is derived from the Old French subburbe and ultimately from the Latin suburbium, formed from sub, meaning "under", and urbs, meaning "city". In Rome, important people tended to live within the city wall on one of the seven roman hills, while the lower classes often lived outside of the walls and at the foot of the hills. "Under" in later usage sometimes referred variously to lesser wealth, political power, population, or population density. The first recorded usage, according to the Oxford English Dictionary, comes from Wycliffe in 1380, where the form subarbis is used.

Suburb has a different meanings in different parts of the world.

In the United States, Canada, suburb usually refers to a separate municipality, borough, or unincorporated area outside a town or city. This definition is evident in the title of David Rusk's book Cities Without Suburbs (ISBN 0-943875-73-0 ), which promotes metropolitan government. U.S. colloquial usage sometimes shortens the term to 'burb, and "the Burbs" first appeared as a term for the suburbs of Chicago.Fact: date=April 2008

In Ireland and the United Kingdom, suburb merely refers to residential areas outside the city centre, regardless of administrative boundaries. Suburbs in this sense are not separated by open countryside to the city centre. In large cities such as London, suburbs include formerly separate towns and villages which have been gradually absorbed during a city's growth and expansion.

In Australia and New Zealand, suburbs have become formalized as geographic subdivisions of a city and are used by postal services in addressing. In rural areas of Australia their equivalent are called localities (see suburbs and localities). In Australia, the terms inner suburb and outer suburb are used to differentiate between the higher-density suburbs with close proximity to the city center, and the lower-density suburbs on the outskirts of the urban area. Inner suburbs, such as Te Aro in Wellington, Prahran in Melbourne and Ultimo in Sydney, are usually characterised by higher density apartment housing and greater integration between commercial and residential areas.