Urbanization is the process through which populations move from rural to urban areas, enabling cities and towns to grow. It refers to the population shift from rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. Urbanization is often responsible for the myriad of modern problems facing humanity. Although the two concepts are sometimes used interchangeably, urbanization should be distinguished from urban growth. Urbanization refers to the proportion of the total national population living in areas classified as urban, whereas urban growth strictly refers to the absolute number of people living in those areas.
Urbanization is relevant to a range of disciplines, including urban planning, geography, sociology, architecture, economics, education, statistics, and public health. The phenomenon has been closely linked to globalization, modernization, industrialization, and the sociological process of rationalization. Urbanization can be seen as a specific condition at a set time (e.g. the present urbanization level in a country) or as an increase in that condition over time (e.g. the increase in urbanization in a country over the past century) .
Urbanization has both positive and negative effects. It can provide social and economic advantages such as better education, health care, sanitation, housing, business opportunities, and transportation. However, it can also lead to urban sprawl, environmental degradation, and social inequality. Urbanization affects relatively little land cover on a national scale, but it has a significant ecological footprint. Even small amounts of urban development can have large effects on stream ecosystems.
