The purpose of this article is to introduce several distinctions between types of people on the move, their relative frequency, and the role the United Nations (UN) has played to develop guidelines to increase their protection. The article begins with distinctions between international migrants, refugees, asylum-seekers, internally displaced persons, and stateless persons. In total, there are an estimated 272 million people living outside their country of origin. This number includes 25.9 million refugees and 3.5 million asylum-seekers. Because these individuals experience forced migration, they are vulnerable to a myriad of challenges, and are in need of international protection. The United Nations has been at the forefront of protecting these vulnerable populations since the Universal Declaration of Human Rights. Several key doctrines that were subsequently written to protect immigrants, forcibly displaced individuals, and stateless persons are introduced to the reader.