Migration is a form of spatial mobility of population between one geographical unit and another involving a permanent change of residence (UN, 1958). The census of India defines migration by place of birth or residence. If a person was born at a place other than the place of enumeration, then he is treated as migrant. For a large country like India, the study of movement of population in different parts of the country helps in understanding the dynamics of the society better. The study describes the factors responsible for migration. In rural areas, due to less employment opportunities, low wages, drought, lack of basic amenities, landlessness, social factors act, people migrate to urban areas to get more employment opportunities, higher income, better wages, better facilities activities. A large part of migrated population particularly in large and metropolitan cities lives in marginal settlements, slums and squatter areas with limited infrastructure services threatening health, environmental degradation of urban areas, traffic and other problems of urban areas. The paper is an attempt to understand the concept of migration, its causes and consequences in India.