A city-state is a self-governing urban center that operates independently from surrounding territories. It typically consists of a city and its immediate agricultural hinterland. Historically, city-states were common in regions like ancient Greece and Mesopotamia, where they functioned as individual political entities. City-states often have their own governments, laws, and military forces. They can vary in size and influence, with some, like Venice or Athens, becoming powerful trade and cultural hubs. The concept of city-states continues to exist today in places like Singapore and Monaco, which maintain their sovereignty while being surrounded by larger nations.