Migration is a wide-ranging term that covers people who move to a foreign country for a certain length of time - not to be confused with short-term visitors such as tourists and traders. People migrate for a variety of reasons.

The definition of ‘forced migration’ describes it as ‘a general term that refers to the movements of refugees and internally displaced people (those displaced by conflicts) as well as people displaced by natural or environmental disasters, chemical or nuclear disasters, famine, or development projects
- See more at: http://www.forcedmigration.org/about/whatisfm#sthash.Nt8KK3wA.dpuf

According to the1951 UN Refugee Convention, refugees are people that moved across an international border and are unable or unwilling to return back to their origin country because of a ‘well-founded fear of persecution on account of race, religion, nationality, membership in a political social group, or political opinion’.