A city-state is a region controlled exclusively by a city. City-states were common in the ancient period and gradually were combined into nations.

The many poleis of ancient Greece are classical examples. Other examples of city-states in history include:

• Sumer
• Phoenician cities and Carthage
• Maya civilization
• Venice and other Italian marine republics
• Ragusa/Dubrovnik
• Szczecin - 12th century
• Wolin - 12th century
• Danzig (1806-1813), (1921-1939)

The term city-state also has the following contemporary usages:

• a city that is a state by itself: the independent states Monaco, Singapore, San Marino and Vatican City
• the states of Germany: Berlin, Bremen and Hamburg
• the Chinese Special Administrative Regions: Hong Kong and Macau.