“Everyone has the right to freedom of movement and residence within the borders of each state. ” Migrations are complex, often global phenomena; migrants depart from specific places and select their destinations from among many cultures (Harzig & Hoerder, 2009). Infact, Demko, Ross & Schnell (1970) empahsize the latter, with defining migration as the most complex component of population change. It provides an important network for the diffusion of ideas and information and indicates symptoms of social and economic change, and can be regarded as a human adjustment to economic, environmental, and social problems (Sinha, 2005). He continues that, in addition, migration is the component of change most difficult to project because of the uncertainty associated with the decision to change one’s place of residence.

Dudley (1970) described population migration as an expression of interaction over space but differs in certain essentail characteristics from other channels of interaction, mainly in terms of commodity, which is being transported. Migration is viewed as a form of individual or group adaptation to perceived changes in environment, according to Sinha (2005). Chapman (1979) considered migration as a good example of relocation diffusion since no body can literally be in two places at once. Harzig & Hoerder (2009) continue to emphasize this fact; that migration implies multiple options: mobility may be many-directional and multiple, temporary or long-term, voluntary or forced. While migration is as old as humanity itself, theories about migration are fairly new according to Hagen-Zanker (2008). One of the early writers on modern migration is Ravenstein, who in the 1880s based his “Laws of Migration” on empirical migration data. This collection of empirical regularities, for example the fact that most migrants only travel short distances, was far from a complete theory of migration. Early migration models (e. g. Zipf, 1946) used the physical concept of gravity and explained migration as a function of the size of the origin and destination population and predicted to be inversely related to distance.

While the early analyses look at aggregate data and often see migration as equilibrating mechanism, the focus since the 1980s is on more elaborate microeconomic models, continues to state Hagen-Zanker (2008). These models analyse individual motivations to migrate, but also consider structural community level factors (e. g. poverty). More modern approaches link the micro and macro level and also include less economic concepts, for example social capital. Another contribution of the more recent literature is the differentiation between causes and perpetuation of migration. The New Economics of Labour Migration developed in the 1980s sees migration as a household decision and includes more explanations for migration. It stands out from the classical theories of migration in that it tries to model the decision-making process more realistically by including a wide range of decision making factors.