A treaty is a formally signed and ratified agreement between two or more nations or sovereigns; a contract between two or more countries that is adhered to by the nations party to it; an international agreement between two or more states that is governed by international law.
In the United States, treaties are federal law and thus preempt state law. The treaty power is granted by Article II, Section 2 of the Constitution, under which the President may make a treaty by and with the advice and consent of the Senate, with the concurrence of two-thirds of those present. To circumvent this requirement, a President may enter informal treaties by executive agreements with the leaders of other nations.
[Last updated in August of 2021 by the Wex Definitions Team]