Another striking feature of the study of migration is that while changes in population size and structure caused by mortality and fertility are never drastic, migration may increase or decrease the size and change the structure of any population quite drastically at any point of time, specially when large numbers move into a particular area or move out of another.

In some ways, the methodology of the study of migration is also quite different from that of either mortality or fertility. But the data required for the study of migration are not easily available.

The study of migration occupies an important place in popu­lation studies, because, in combination with fertility and mortality, it determines the size and the rate of population growth, as well as its structure and characteristics.

Migration also plays an important role in distribution of the population of any country, and deter­mines the growth of the labour force in any area. The measure­ment and analysis of migration is useful in preparing regional population projections.


The study of migration is important not only to demographers but is also of great importance and interest to economists, socio­logists, human geographers, political scientists, legal departments, policy-makers and planners, public administrators, social patholo­gists and social psychologists.

Some of the reasons why persons working in a variety of fields are interested in the study of migration may be elaborated as follows: Migration may be considered as a symptom of basic social change.

In most countries, it has been observed that industrialisation and economic development have been accompa­nied by large-scale movements of people from farm areas to towns, from towns to other towns, and from one country to another.

For instance, countries in Asia, Africa and Latin America, which are at present undergoing technological changes, are experiencing some type of migration from rural to urban areas, and these streams of migration have given rise to metropolitan cities.


Economists are interested in the study of migration because it is related to business cycles, supply of skilled and unskilled workers, growth of industries and the occupational and employment status of the migrants.

Planners and policy-makers are concerned with migration because it is associated with the socio-economic development of the country.

In India and in many other developing countries, one of the side effects of unprecedented population growth as well as industrialisation and economic development is a rapid increase in internal migratory movements.

The emergence of such a massive population phenomenon especially that of rural-urban migration has attracted the attention of planners and policy-makers to the problems arising out of migration.


The Indian Planning Commission recommended as early as in 1956 that studies should be undertaken on problems related to regional development, with special reference to problems of rapid urbanisation.

Sociologists and social psychologists study migration because they are interested in studying the social and psychological problems associated with it, specially those concerning migrants, the people who live in areas from which these migrants come (sending areas) and those who live in areas where migrants arrive (receiving areas).

Data on the age, sex, mother tongue, education and occupation of the migrants are useful to sociologists and social psychologists, for these data enable them to plan programmes in order to solve or control the problems arising out of migration which are social and psychological in nature.

General Terms and Concepts of Migration


As pointed out earlier, the meanings of the terms and concepts used in the study of migration are distinct from those used in common parlance.

The collection and analysis of migration data are carried out on the basis of a standard set of definitions of concepts built up over the years by demographers working in the field of migration. It is, therefore, essential to get acquainted with the terms and concepts used in the study of migration.

It is customary to study migration with respect to (1) Internal migration and (2) International migration. Internal migration is the migration of persons within a country, while international migration refers to the movement of people from one country to another.

In-migration and Out-migration


In-migration refers to movement into a particular area, while out-migration refers to movement of out of a particular area, both referring to movements within a country, that is, internal migration.

Thus migrants who come from Tamil Nadu to Maharashtra are considered to be in- migrants for Maharashtra and out-migrants for Tamil Nadu.

Each move is either immigration or an in-migration with respect to the place of destination and emigration or out-migration with respect to the place of origin and departure.