Cities We Live In
Urbanization Proportions, and Top 500 Biggest Urban Areas in 2015.
Urbanization primarily means the process of a city expanding, and the expansion stems from an increase in population such as new birth or, more commonly, the migration of new settlers moving from suburban or rural areas to urban areas. The increase of population results in the growth of the city outward and upward, and thus it eventually turns into a hub that encompasses the connection between residential districts and commercial districts, which is called a metropolis. It is an agglomeration of urban areas that has become immensely complex through the urbanization; it ends up with blurring the border line that determines the boundary of a city as an administrative or legal status.
Data source : United Nation, Department of Economic and Social Affairs