Migration is a result of an inter-play of a large number of factors. Generally factors affecting migration can be grouped in to two categories of Push and Pull factors.
The push factors are responsible for making people move from their original place of living. The pull factors are responsible for attracting people to some particular areas. Unless both these factors are operating simultaneously, no migration of people can be possible. The push and pull factors include the economic, social and political components.
The people generally like to live in those areas where they can make their livelihood. Thus, they would like to move away from areas of poor soils, less developed means of transport, low levels of industrialization and less job opportunities. These are the push factors.
On the other hand, the areas offering good employment, better living standard attract large number of people. These are the pull factors. Thus, all areas of fertile soil, deposits of minerals, better means of transportation and communication and higher levels of development of industries and urban areas provide more means of making a living.
A large number of people move to the cities like Delhi, Mumbai, Kolkata and Chennai from neighbouring and different parts of the country like Bihar, Orissa, Uttar Pradesh where opportunities are less. The most important factor for which they move is the expected improvement in their economic conditions. Many are attracted by an apparent glare of city life with all its modern comforts and attractions.
Man is a social being and he likes to live with his kith and kin. Generally the people having a common religion or language or social customs like to live together. On the other hand a person would like to migrate to some other place if he is living among the people belonging to some other culture or customs.
Many people migrate to places of religious importance. Migration of people to places like Badrinath, Tirupati and Varanasi though generally temporary is due to religious factors. The impact of the social factors is more clearly seen in the concentration of people belonging to a particular community in one locality of urban area or in a particular city. Religious or social suppression of the minority communities can be an important push factor if the majority community is not tolerant to the other community.
Age is the important demographic factor. Young population is more mobile than the children and old age population. This is because young people mostly move either for work or better opportunities or further study.
Political factors related to the government policy are responsible for migration. This factor is becoming increasingly important in the modern times. Government can influence the incidence rates and directions of the migrations to a great extent.
In some cases the minority communities are discriminated against and they are thus forced out of the countries. Partition of India into India and Pakistan at the time of independence resulted in large scale migration of people between the two countries.