A nation is a group of people who share the same culture, history, language or ethnicity. The word can also be used for the population of a country.

The word nation comes from a Latin language word meaning "birth" or "place of birth." The adjective is national.

Some nations are people with a particular belief, such as the Vatican City, or ethnic group, such as Armenia. Others share an idea, such as Democracy in the United States or Communism in China.

Some nations are controlled by a small minority who have all the power, such as Saudi Arabia, who hold the nation together with the use of this power.

Some of these may also be combined. The highest lawful authority of most nations is a constitution, which is a document which states clearly what kinds of power the rulers have and how new laws must be made. Many others are ruled by a single person who holds an "office" (position), such as a King or Pope, or from a long legal tradition without an official Constitution, such as the United Kingdom.

• State
• Nation state
• Country
• Nationalism
• Political economy
• Constitutional economics