According to the United Nations Population Division, an international migrant is someone who has been living for one year or longer in a country other than the one in which he or she was born. This means that many foreign workers and international students are counted as migrants. Additionally, the UN considers refugees and, in some cases, their descendants (such as Palestinians born in refugee camps outside of the Palestinian territories) to be international migrants.
For the purposes of this interactive feature, estimates of the number of unauthorized immigrants living in various countries also are included in the total counts. On the other hand, tourists, foreign-aid workers, temporary workers employed abroad for less than a year and overseas military personnel typically are not counted as migrants.