A treaty is a written agreement between two or more parties, which may be countries or other important groups, about any subject. Treaties usually settle or avoid disputes.
Countries may agree to end a war or to declare war on a common enemy by promising to come to the aid of another country if it is attacked. They may allow allow each other's citizens or merchandise to cross borders freely, such as the European Union, which is the result of treaties between most countries in Europe.
In general, treaties are usually used to settle disputes, or to avoid disputes.
