A formal written agreement between states that creates binding legal obligations is a treaty. Treaties cover peace settlements, alliances, trade, human rights, environmental protection, and countless technical subjects.

Negotiation is followed by signature and then by ratification according to each state’s constitutional process. Once in force, treaties bind the parties under international law. Interpretation, amendment, and withdrawal follow specified or customary rules. Domestic legal systems differ in how directly treaties become enforceable in national courts.

Treaties are primary instruments of international cooperation and order. Powerful states sometimes prefer informal arrangements that are easier to adjust; weaker states often prefer the clarity and equality of formal treaty commitments. Compliance is imperfect and enforcement decentralized, yet the dense network of treaties structures much of modern international relations.

A ratified treaty converts a political understanding into a lasting legal commitment.