Emigration is the act of leaving one's resident country with the intent to settle elsewhere. Conversely, immigration describes the movement of persons into one country from another. Both are acts of migration across national boundaries.
Demographers examine push and pull factors for people to be pushed out of one place and attracted to another. There can be a desire to escape negative circumstances such as shortages of land or jobs, or unfair treatment. People can be pulled to the opportunities available elsewhere. Fleeing from oppressive conditions, being a refugee and seeking asylum to get refugee status in a foreign country, may lead to permanent emigration.
Involuntary migration refers to groups that are forced to abandon their native country, such as by enforced population transfer or the threat of ethnic cleansing.
Patterns of emigration have been shaped by numerous economic, social, and political changes throughout the world in the last few hundred years. For instance, millions of individuals fled poverty, violence, and political turmoil in Europe to settle in the Americas and Oceania during the 18th, 19th, and 20th centuries. Likewise, millions left South China in the Chinese diaspora during the 19th and early 20th centuries.
Demographers distinguish factors at the origin that push people out, versus those at the destination that pull them in. Motives to migrate can be either incentives attracting people away, known as pull factors, or circumstances encouraging a person to leave.
Some countries restrict the ability of their citizens to emigrate to other countries. After 1668, the Qing Emperor banned Han Chinese migration to Manchuria. In 1681, the emperor ordered construction of the Willow Palisade, a barrier beyond which the Chinese were prohibited from encroaching on Manchu and Mongol lands.