‘Who is a migrant?’ looks at defining and measuring migration. Migrants can be categorized, based on whether they migrated voluntarily or involuntarily, whether they are economic or political migrants, or their legal status. These categories, while somewhat useful, tend to blur in reality, and the situation migrants find themselves in can change quickly. It is difficult to measure migration for a number of reasons, and any statistics produced are open to misuse. People can stop being migrants by returning to their own country or by obtaining citizenship of the host country. National policies on migration and citizenship balance assimilation with multiculturalism. Migrant communities often form diasporas and maintain transnational attachments.