High Quality Content by WIKIPEDIA articles! Suburbs, usually referring to a residential area, are defined in various different ways around the world. They can be the residential areas of a large city, or separate residential communities within commuting distance of a city. 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.