This chapter will identify and elaborate on the migratory phenomenon, or migration, in general, indicating the displacement of one person or group of people, which can happen within the same country (internal migration) or through crossing international borders (international migration). International migration, therefore, involves the country of provenance/origin of the person and one or more countries of transit, and finally, a country of destination. The term migration, therefore, embraces all types of displacements without distinction in terms of temporal, spatial, and causal amplitude. It includes economic, environmental, forced migration, family reunification, and other variants. Consequently, the migrant is a person who, for whatever reason, moves from the country of origin. However, the definition of a migrant is not universally accepted.