A principality is a territory ruled by a prince or princess. Throughout history, Europe had many principalities: small kingdoms or regions where a prince held power, sometimes independently and sometimes under a larger king or emperor. Monaco, a tiny country on the Mediterranean coast of France, is still a principality today, ruled by Prince Albert II.

The word comes from prince, but don't picture fairy tale princes in castles (though some principalities had those). Think instead of political leaders who governed real territories with laws, armies, and citizens. In medieval times, the Holy Roman Empire contained dozens of principalities, each controlling its own cities and lands. Some principalities were wealthy and powerful, while others were barely larger than a single town.

Wales, part of the United Kingdom, is sometimes called a principality because the heir to the British throne traditionally holds the title Prince of Wales, though Wales is governed the same way as England and Scotland. The word can also refer to the position or authority of a prince, as when someone inherits a principality. While most principalities have disappeared as nations merged into larger countries, the word reminds us that Europe's political map once looked like a patchwork quilt of small, independent territories, each with its own ruler.