Urbanization is the action and effect of urbanizing land to add easy access to basic services (water supply, gas, electricity, etc.), in addition to dividing the land and adding streets. Generally, the space on which this change is carried out was previously wild land, or of rustic use. The father of the concept in Spanish, Ildefonso Cerdá defined it like this:

In demography, urbanization or the urbanization process refers to the process by which a migration of the population occurs from the rural environment (rural exodus) to the urban environment (cities). Urbanization can produce depopulation of rural areas.[2]​.

In architecture, urbanization refers to the planning and subsequent construction of communication routes, streets, squares, buildings - whether homes, public buildings or industrial estates - that convert a rural and uninhabited space into a built and inhabited or intensely used space.

In his introduction, Ildefonso Cerdá traces back to the Roman concept of urbs ​​the etymological reason for the new concept that he was defining while emphasizing the difference with the Latin concept of civitas. Both terms in current Spanish are translated as city, but, however, while the second is limited to the social aspect, to the "citizen", the first focuses on the physical and material aspect of the city:.

In demography, the phenomenon by which migration from the rural environment (countryside) to the urban environment (cities) is called urbanization or the urbanization process is called urbanization. This phenomenon gains strength at the end of the century but it is during the century and when it reaches great importance. Thus, in 1950, 30% of the world's population was urban - 70% of the population lived in rural areas. In 2007, the planet's urban population surpassed the rural population for the first time in history. In 2018 the urban population reaches 55% of the world population and it is estimated that in 2050 66% (two thirds) of the world population will live in cities. This phenomenon is producing depopulation in many rural areas. Urbanization brings with it not only the depopulation of rural areas, but also a drop in the fertility rate.[2]​.