Citizenship is a relationship between an individual and a state to which the individual owes allegiance and in turn is entitled to its protection.

Each state determines the conditions under which it will recognize persons as its citizens, and the conditions under which that status will be withdrawn. Recognition by a state as a citizen generally carries with it recognition of civil, political, and social rights which are not afforded to non-citizens.

In general, the basic rights normally regarded as arising from citizenship are the right to a passport, the right to leave and return to the country/ies of citizenship, the right to live in that country and to work there.

Some countries permit their citizens to have multiple citizenships, while others insist on exclusive allegiance. A person who does not have citizenship of any state is said to be stateless, while one who lives on state borders whose territorial status is uncertain is a border-lander.