Human migration is movement by humans from one place to another, sometimes over long distances or in large groups. Historically this movement was nomadic, often causing significant conflict with the indigenous population and their displacement or cultural assimilation. Only a few nomadic people have retained this form of lifestyle in modern times. Migration has continued under the form of both voluntary migration within one's region, country, or beyond and involuntary migration (which includes the slave trade, trafficking in human beings and ethnic cleansing). People who migrate into a territory are called immigrants, while at the departure point they are called emigrants. Small populations migrating to develop a territory considered void of settlement depending on historical setting, circumstances and perspective are referred to as settlers or colonists, while populations displaced by immigration and colonization are called refugees
According to International Organization for Migration, man "no universally accepted definition for (migrant) exists. The term migrant was usually understood to cover all cases where the decision to migrate was taken freely by the individual concerned for reasons of "personal convenience" and without intervention of an external compelling factor; it therefore applied to persons, and family members, moving to another country or region to better their material or social conditions and improve the prospect for themselves or their family. The United Nations defines 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. Under such a definition, those travelling for shorter periods as tourists and businesspersons would not be considered migrants. However, common usage includes certain kinds of shorter-term migrants, such as seasonal farm-workers who travel for short periods to work planting