A built-up area is an area of land that has been developed for human habitation, usually with a high population density. It can refer to a TOWN or city, or to a more rural area with a higher population than the surrounding countryside. The term 'TOWN' is typically used to refer to a built-up area with a population of less than 100, 000 people, while 'URBAN' is used to refer to a built-up area with a population of more than 100, 000 people.