The word migration is likely to bring to mind a stereotype familiar to American culture: people voluntarily coming into another country in search of work and other opportunities. Yet this is only one aspect of the meaning of migration as understood by anthropologists. Migration, put simply, is movement from one place to another that reestablishes a household, either permanently or temporarily. Examples of migration include seasonal movements in search of work, temporary movements due to a crisis or local challenges, transnational movements from one nation to another, and even occasional moves from one household to another over a lifetime (sometimes referred to as internal versus external migration). Migrants, by extension, are simply people who move. Other than those relatively few people who are living in the same house they were born into, we are all migrants of one sort or another. Within this larger category of migrants, immigrants are individuals who move permanently from one country (where they are referred to as emigrants) to another country (where they are called immigrants).
The human species, along with our ancestors, has practiced migration from our earliest origins. It is part of who we are. Most living species migrate in some way, but humans move more widely than other species and modify the landscape the most through their movements. Human migration impacts the world in innumerable ways.