It is generally characterized by some form of political participation, although the extent of such participation can vary considerably from minimal duties such as voting to active service in government. It is often based on, or a function of, some form of military service or expectation of future military service. It generally describes the relation between a person and an overall political entity such as a city-state or nation and signifies membership in that body. Citizenship bonds extend beyond basic kinship ties to unite people of different genetic backgrounds, that is, citizenship is more than a clan or extended kinship network. While citizenship has varied considerably throughout history, there are some common elements of citizenship over time. In modern democracies, citizenship has contrasting senses, including a liberal-individualist view emphasizing needs and entitlements and legal protections for essentially passive political beings, and a civic-republican view emphasizing political participation and seeing citizenship as an active relation with specific privileges and obligations. In the Middle Ages in Europe, citizenship was primarily identified with commercial and secular life in the growing cities, and it came to be seen as membership in emerging nation-states. In Roman times, citizenship began to take on more of the character of a relationship based on law, with less political participation than in ancient Greece but a widening sphere of who was considered to be a citizen.

While there is disagreement about when the relation of citizenship began, many thinkers point to the early city-states of ancient Greece, possibly as a reaction to the fear of slavery, although others see it as primarily a modern phenomenon dating back only a few hundred years.

There is a general view that citizenship in ancient times was a simpler relation than modern forms of citizenship, although this view has been challenged. Citizenship is generally identified not as an aspect of Eastern civilization but of Western civilization. History of citizenship describes the changing relation between an individual and the state, known as citizenship. A hoplite's armor signified its owner's social status as well as his service to the community. Ancient Athenian armor from the 6th century BCE called a greave covered a citizen-soldier's knee and lower leg.

Aristotle on citizenship