A city-state is a sovereign state, also described as a type of small independent country, that usually consists of a single city and its dependent territories. Historically, this included cities such as Rome, Athens, Carthage, and the Italian city-states during the Renaissance.

As of 2019, only a handful of sovereign city-states exist, with some disagreement as to which are city-states. A great deal of consensus exists that the term properly applies currently to Monaco, Singapore, and Vatican City. City states are also sometimes called microstates which however also includes other configurations of very small countries, not to be confused with micronations.

Several non-sovereign cities enjoy a high degree of autonomy, and are sometimes considered city-states. Hong Kong and Macau, along with independent members of the United Arab Emirates, most notably Dubai and Abu Dhabi, are often cited as such.

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