A treaty is a formal written agreement between two or more countries. When nations sign a treaty, they're making serious promises to each other about how they'll behave, what they'll do together, or how they'll solve a problem.

Treaties cover all sorts of situations. A peace treaty ends a war, like the Treaty of Versailles that ended World War I. A trade treaty sets rules for buying and selling goods between countries. An environmental treaty might commit nations to protecting endangered species or reducing pollution. The North Atlantic Treaty created NATO, an alliance where member countries promised to defend each other.

Creating a treaty takes careful negotiation. Representatives from each country meet, discuss terms, and work out details everyone can accept. Once leaders sign a treaty, it becomes binding, meaning the countries are expected to keep their promises. Breaking a treaty damages a country's reputation and makes other nations less willing to trust them in the future.