The process by which rural and sparsely distributed human settlements and populations into dense agglomerations in the form of towns and cities. Urbanization may refer to a housing and human settlement agglomeration in situ, as well as human migration from rural to urban areas.
Urbanization is predominantly a process by which towns and cities are (1) formed and (2) become larger as more people begin living and working in areas closer to centers of production and consumption. “Urbanization” may refer to the two concepts and their corresponding processes interchangeably.
Urbanization is distinguished from urban growth. That is, urbanization is “the proportion of the total national population living in areas classed as urban,” while urban growth refers to “the absolute number of people living in areas classed as urban.” The United Nations projected that half of the world`s population would live in urban areas at the end of 2008. It is predicted that by 2050 about 64% of the developing world and 86% of the developed world will be urbanized.
 Cecilia Tacoli, Gordon McGranahan and David Satterthwaite, Urbanisation, rural-urban migration and urban poverty (London: International Institute for Environment and Development, 2015).