An international agreement made between states in written form under international law whether in one or more instruments is defined as

The Vienna Convention on the Law of Treaties signed in 1969 is regarded as the framework treaty of treaties. It provides detailed rules on how treaties are negotiated adopted applied and terminated among states. For example it clarifies rules of consent reservations and withdrawal. It plays an essential role in maintaining consistency in international law. The convention has been ratified by over one hundred countries and ensures that agreements between nations follow uniform principles. It also provides peaceful methods for resolving disputes about treaty interpretation.