Citizenship is the state of being a citizen of a particular social, political, national, or human resource community. The term describing all citizens as a whole is citizenry.

In law, citizenship denotes a link between an individual and a state. Under international law, citizenship is synonymous to nationality, although the two may have different meanings under national law. A person who does not have citizenship in any state is stateless.

Generally citizenship is seen as the relation between an individual and a particular nation. For example, a person can be described as being a citizen of Australia or Egypt or Ireland. While in ancient Greece the main political entity was the city-state, during the past five hundred years with the rise of the nation-state, citizenship is most closely identified with being a member of a particular nation. To some extent, certain entities cross national boundaries such as trade organizations, non-governmental organizations as well as multi-national corporations, and sometimes the term "citizen of the world" has been applied in the sense of people having less ties to a particular nation and more of a sense of belonging to the world in general, but generally citizenship is seen as a marker denoting membership in a nation.