largest city

See historical urban community sizes for historical data. This is a list of the most populous cities of the world defined according to the concept of city proper. The list ranks the world's urban municipal units (or well-defined statistical groupings of such units) according to population. Note that the populations listed are for the city proper and not for the urban area nor the metropolitan area. For a list of the most populous urban and metropolitan areas, see List of urban areas by population and List of metropolitan areas by population. Statistical definitions for each city and approximate surface area are also indicated.
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The "size" of a city can refer to either its physical extent or its population. Furthermore, there are three main ways of delineating the boundaries of a city:A morphological definition based on the urban area, which is usually defined as the continuous built-up area with the maximum allowable gap between structures of typically 200 m. The delineation is usually done using population density criteria, or by satellite/aerial maps, without regard to political boundaries. For statistical convenience, such areas are sometimes adjusted to appropriate administrative limits, sometimes including rural areas within the adjusted boundaries (urban agglomeration).
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