Migration as the physical transition of an individual or a group from one society to another. This transition normally involves abandoning one social setting and entering another, and different one. Migration as an inflow or outflow of population from a definite region to another region for a permanent or semi-permanent settlements. A person who moves out from one village to another village or town is termed as migrant provided the movement is not short term due to causal leave, visiting etc. A human migration therefore implies the movement of people with the goal of long-term relocation. Thus, commuting, vacations, casual leave, visiting are not included in migration. Migrant as an individual who has resided in a foreign country for more than one year irrespective of the causes, voluntary or involuntary, and the means, regular or irregular, used to migrate. This implies those who moved for shorter periods as tourists and business persons would not be called as migrants. This conceptual paper will focus on the different theories of migration and its impacts to the nation. The study is based on secondary sources of data from books, various academic journals and published factsheets to understand the migration theories in the globe.

Keywords: Migration, Residence, Economic, Development & Population