A country is land that is controlled by a single government. Countries are also called nations, states, or nation-states. Countries can be large or small. Australia, Brazil, Canada, China, Russia, and the United States are large countries spread over millions of square miles. The world’s smallest country, Vatican City, covers less than 1 square mile (2.6 square kilometers).
From: https://kids.britannica.com/kids/article/country/391002