This article defines citizenship and discusses its three basic theoretical traditions. We then delve into seven important areas of citizenship in terms of how: (1) rights and obligations have grown, (2) identities are framed for new citizens; (3) citizenship is universal or particular, or individual or group-based; (4) citizenship is contained within boundaries and externalized to the global; (5) citizenship is structured into various regime types; (6) citizenship has moved from being a status to involving people in a process; and (7) citizenship may develop in the future with new technologies.