International law is a group of rules and norms argued to apply between sovereign states and other entities that are recognized as international actors. Some may be from international agreements and treaties, others from argued international customs and traditions.
The rules and norms usually operate through mutual consent, since there is no universally accepted authority to enforce them upon sovereign states, although ignoring the rules and the norms may possibly influence some other sovereign states to decide to take various coercive actions, such as sanctions or military interventions.
A sovereign state may permit some parts of international law to become parts of the national legal system of the sovereign state.
"Treaty" may refer to a binding formal agreement that establishes obligations between two or more subjects of international law. However, for example peace treaties can involve other parties and existed before the concept of international law.