A city-state is an independent or autonomous entity whose territory consists of a city which is not administered as a part of another local government. A city-state can also be defined as a central city and its surrounding villages, which together follow the same law, have one form of government, and share languages, religious beliefs, and ways of life.

Historical examples include the oldest known Sumerian cities of Mesopotamia and Ur, the Phoenician cities of Canaan (such as Tyre and Sidon), the Berber city-states of the Garamantes, the city-states of ancient Greece (the poleis such as Athens, Sparta, Thebes, and Corinth), the Roman Republic which grew from a city-state into a great power, the Maya of pre-Columbian Mesoamerica (including sites such as Chichen Itza and El Mirador), the central Asian cities along the Silk Road, Venice, Croatian city-state of Ragusa (Dubrovnik) and many others. The Viking colonial cities in medieval Ireland, most importantly Dublin, have recently been classed as genuine city-states.