Human displacement is an old phenomenon; however, the dislocation of people in the twenty-first century has been unprecedented. At the end of 2019, over 260 million people were living outside their countries of birth. Some are forced to relocate--by violence, wars, hunger, persecution, and other causes--and some are voluntary migrants. A single term cannot define who they are or why they are on the move. For those uprooted by force, the psychological...