Indian Diaspora
During colonial period (British period) millions of the indentured labourers were sent to different parts of the world to work as plantation workers. All such migrations were covered under the time-bound contract known as Girmit Act (Indian Emigration Act). However, the living conditions of these indentured labourers were not better than the slaves. The second wave of migrants ventured out into the neighbouring countries in recent times as professionals, artisans, traders and factory workers, in search of economic opportunities to Thailand, Malaysia, Singapore, Indonesia, Brunei and African countries, etc. and the trend still continues. There was a steady outflow of India’s semi-skilled and skilled labour in the wake of the oil boom in West Asia in the 1970s. There was also some outflow of entrepreneurs, professionals, businessmen to Western Countries. Third wave, of migrant was comprised professionals like doctors, engineers (1960s onwards), software engineers, management consultants, financial experts, media persons (1980s onwards), and others migrated to countries such as USA, Canada, UK, Australia, New Zealand and Germany, etc. These professional enjoy the distinction of being one of highly educated, the highest earning and prospering groups. After liberalisation, in the 90s education and knowledge–based Indian emigration has made Indian Diaspora one of the most powerful diasporas in the world. In all these countries, Indian diaspora has been playing an important role in the development of the respective countries.

Migration
Migration was recorded beginning from the first Census of India conducted in 1881. This data were recorded on the basis of place of birth. However, the first major modification was introduced in 1961 Census by bringing in two additional components viz; place of birth i.e. village or town and duration of residence (if born elsewhere). Further in 1971, additional information on place of last residence and duration of stay at the place of enumeration were incorporated. Information on reasons for migration were incorporated in 1981 Census.

Streams of Migration
A few facts pertaining to the internal migration (within the country) and international migration (out of the country and into the country from other countries) are presented here. Females predominate the streams of short distance rural to rural migration in both types of migration. Contrary to this, men predominate the rural to urban stream of inter-state migration due to economic reasons. Apart from these streams of internal migration, India also experiences immigration from and emigration to the neighbouring countries.
Indian migration, four streams are identified:
(a) rural to rural
(b) rural to urban
(c) urban to urban  and
(d) urban to rural.

In India, during 2001, out of 315 million migrants, enumerated on the basis of the last residence, 98 million had changed their place of residence in the last ten years. Out of these, 81 million were intrastate migrants. The stream was dominated by female migrants. Most of these were migrants related to marriage. Census 2001 has recorded that more than 5 million person have migrated to India from other countries. Out of these, 96 per cent came from the neighbouring countries: Bangladesh (3.0 million) followed by Pakistan (0.9 million) and Nepal (0.5 million). Included in this are 0.16 million refugees from Tibet, Sri Lanka, Bangladesh, Pakistan, Afghanistan, Iran, and Myanmar. As far as emigration from India is concerned it is estimated that there are around 20 million people of Indian Diaspora, spread across 110 countries.

Spatial Variation in Migration
Some states like Maharashtra, Delhi, Gujarat and Haryana attract migrants from other states such as Uttar Pradesh, Bihar, etc. Maharashtra occupied first place in the list with 2.3 million net in-migrants, followed by Delhi, Gujarat and Haryana. On the other hand, Uttar Pradesh (-2.6 million) and Bihar (-1.7 million) were the states, which had the largest number of net out-migrants from the state.

Causes of Migration
People, generally are emotionally attached to their place of birth. But millions of people leave their places of birth and residence. There could be variety of reasons. These reasons can be put into two broad categories : (i) push factor, these cause people to leave their place of residence or origin; and (ii) pull factors, which attract the people from different places. In India people migrate from rural to urban areas mainly due to poverty, high population pressure on the land, lack of basic infrastructural facilities like health care, education, etc. Apart from these factors, natural disasters such as, flood, drought, cyclonic storms, earthquake also reasons for migration,

On the other hand, there are pull factors which attract people from rural areas to cities. The most important pull factor for majority of the rural migrants to urban areas is the better opportunities, availability of regular work and relatively higher wages. Better opportunities for education, better health facilities and sources of entertainment, etc. are also quite important pull factors. Work and employment have remained the main cause for male migration (38 per cent) while it is only three per cent for the females. Contrary to this, about 65 per cent of females move out from their parental houses following their marriage. This is the most important cause in the rural areas of India except in Meghalaya where reverse is the case.

Consequences of Migration
Migration is a response to the uneven distribution of opportunities over space. People tend to move from place of low opportunity and low safety to the place of higher opportunity and better safety. This, in turn, creates both benefits and problems for the areas, people migrate from and migrate to. Consequences can be observed in economic, social, cultural, political and demographic terms.

Economic Consequences
A major benefit for the source region is the remittance sent by migrants. Remittances from the international migrants are one of the major sources of foreign exchange. In 2002, India received US$ 11 billion as remittances from international migrants. Punjab, Kerala and Tamil Nadu receive very significant amount from their international migrants. The amount of remittances sent by the internal migrants is very meagre as compared to international
migrants, but it plays an important role in the growth of economy of the source area. Remittances are mainly used for food, repayment of debts, treatment, marriages, children’s education, agricultural inputs, construction of houses, etc. For thousands of the poor villages of Bihar, Uttar Pradesh, Orissa, Andhra Pradesh, Himachal Pradesh, etc. remittance works as life blood for their economy. Migration from rural areas of Eastern Uttar Pradesh, Bihar, Madhya Pradesh and Orissa to the rural areas of Punjab, Haryana, Western Uttar Pradesh accounted for the success of their green revolution strategy for agricultural development.

Besides this, unregulated migration to the metropolitan cities of India has caused overcrowding. Development of slums in industrially developed states such as Maharashtra, Gujarat, Karnataka, Tamil Nadu and Delhi is a negative consequence of unregulated migration within the country.

Demographic Consequences
Migration leads to the redistribution of the population within a country. Rural urban migration is one of the important factors contributing to the population growth of cities. Age and skill selective out migration from the rural area have adverse effect on the rural demographic structure. However, high out migration from Uttaranchal, Rajasthan, Madhya Pradesh and Eastern Maharashtra have brought serious imbalances in age and sex composition in these states.

Social Consequences
Migrants act as agents of social change. The new ideas related to new technologies, family planning, girl’s education, etc. get diffused from urban to rural areas through them. Migration leads to intermixing of people from diverse cultures. It has positive contribution such as evolution of composite culture and breaking through the narrow considerations and widens up the mental horizon of the people at large. But it also has serious negative consequences such as anonimity, which creates social vacuum and sense of dejection among individuals. Continued feeling of dejection may motivate people to fall in the trap of anti-social activities like crime and drug abuse.

Environmental Consequences
Overcrowding of people due to rural-urban migration has put pressure on the existing social and physical infrastructure in the urban areas. This ultimately leads to unplanned growth of urban settlement and formation of slums shanty colonies. Apart from this, due to over-exploitation of natural resources, cities are facing the acute problem of depletion of ground water, air pollution, disposal of sewage and management of solid wastes.

Others
Migration (even excluding the marriage migration) affects the status of women directly or indirectly. In the rural areas, male selective out migration leaving their wives behind puts extra physical as well mental pressure on the women. Migration of ‘women’ either for education or employment enhances their autonomy and role in the economy but also increases their vulnerability. If remittances are the major benefits of migration from the point of view of the source region, the loss of human resources particularly highly skilled people is the most serious cost. The market for advanced skills has become truly a global market and the most dynamic industrial economies are admitting and recruiting significant proportions of the highly trained professionals from poor regions. Consequently, the existing underdevelopment in the source region gets reinforced.