International law is a set of rules and principles that govern the relationships between states and other actors in the international system. International law provides a framework for the peaceful resolution of disputes and the protection of the rights and interests of states and individuals. International law is developed through treaties, customary practice, and the judicial decisions of international courts and tribunals, and is designed to promote stability, predictability, and cooperation in the international system.
Source: Brierly, J. L. (1963). The law of nations: An introduction to the international law of peace. Oxford University Press.