Urbanization or urbanisation is the increase over time in population or extent of cities and towns. Urbanisation has profound effects on the ecology of a region and on its economy. Urban sociology also observes that people's psychology and lifestyles change in an urban environment.
It can thus represent a level of urban population relative to total population of the area, or the rate at which the urban proportion is increasing. Both can be expressed in percentage terms, the rate of change expressed as a percentage per year, millennia or period between censuses. Urbanization can result from either:
-an increase in the extent of urban areas
-an increase in the density of urban areas.
For instance, the United States or United Kingdom have a far higher urbanisation level than China, India or Nigeria, but a far slower annual urbanisation rate, since much less of the population is living in a rural area while in the process of moving to the city.
Australia is at the opposite of the former two in terms of urbanisation rate but also the latter three in urbanisation level, making it one of the most urbanised countries in the world.
The rate of urbanisation over time is distinct from the rate of urban growth, which is the rate at which the urban population or area increases in a given period relative to its own size at the start of that period. The urbanisation rate represents the increase in the proportion of the urban population over the period.
In terms of a place, urbanisation means increased spatial scale and/or density of settlement and/or business and other activities in the area over time. The process could occur either as natural expansion of the existing population (usually not a major factor since urban reproduction tends to be lower than rural),