Forced migration (also called displacements) is when people are made to leave their home or homeland. It is usually caused by violence, persecution, danger, or because an authority (such as a government) has told people to move. People are removed either by force or because of a threat or command. A person who has become forced to migrate is called a "forced migrant" or "displaced person". They may be called a refugee, but that term has a specific legal definition.