Because everything can't be all in the same place. There are advantages and drawbacks to everything. In a town or a city, everything is nearby, but it can cost a lot to live there. And it might be noisy, polluted, lots of crime and things like that.
So people start to look for someplace to live that is cheaper, roomier, safer, but still in reach of the town - and then you get suburbs.
Suburbs
Northern suburbs, Southern suburbs, Western suburbs, Eastern suburbs.
The Suburbs ended in 1987.
28 suburbs
Of or pertaining to suburbs; inhabiting, or being in, the suburbs of a city., One who dwells in the suburbs.
Brown VS the board of education
Lost in the Suburbs was created in 1948.
Southern Suburbs was created in 1979.
Bomb the Suburbs was created in 1994.
Nelson Suburbs was created in 1967.
The Suburbs EP was created in 1978.
Western Suburbs was created in 1906.