Everyone has the right to freedom of movement and residence within the borders of each state. Everyone has the right to leave any county, including his own, and to return to his country. Everyone has the right to seek and to enjoy in other countries asylum from persecution. (Universal Declaration of Human Rights, Article 13 and 14).
On the one hand, some people move to another place out of their choice, to join their family, in search of a new opportunity or to go to a favorite place. On the other hand, others do so out of necessity, to escape from conflict, persecution, human rights violations, discrimination based on sexual orientation, or risks of disasters caused by environmental factors.