In Citizenship: What Everyone Needs to Know, legal scholar Peter J. Spiro explains citizenship through accessible terms and questions: what citizenship means, how you obtain citizenship (and how you lose it), how it has changed through history, what benefits citizenship gets you, and what obligations it extracts from you-all in comparative perspective. He addresses how citizenship status affects a person's rights and obligations, what it means to be stateless, the refugee crisis, and whether or not countries should terminate the citizenship of terrorists. He also examines alternatives to national citizenship, including sub-national and global citizenship, and the phenomenon of investor citizenship. Spiro concludes by considering whether nationalist and extremist politics will lead to a general retreat from state-based forms of association and the end of citizenship as we know it. Ultimately, Spiro provides historical and critical perspective to a concept that is a part of our everyday discourse, providing a crucial contribution to our understanding of a central organizing principle of the modern world.