Urbanization is a part of the development process. The change of population from rural areas to urban areas is a strong measure of economic development. In backward stagnant societies, the process of urbanization is almost slow because cities are not able to provide employment for people living in rural areas. However, the rapid migration of rural population to cities is only for the purpose of getting employment and in this situation the emphasis is on labour intensive industries rather than capital intensive industries. In contrast, the pace of urbanization slows down when the ratio of the total water level to the urban population reaches a very high level. This situation has come to the fore in a total of 30 countries, which are called developed industrial countries. Description Physical expansion of urban areas or increase in its area, population etc. is called 'urbanization'. This is a global change. The paper tries to focus on pattern and extent of rural – urban migration.