The traditional classifications of organizations that play a part in international law include governments, intergovernmental organizations (IGOs), and nongovernmental organizations (NGOs). Intergovernmental organizations are created by states through multilateral treaties that act like a constitution in that the states parties are creating an organization for some purpose.
IGOs usually have a governing structure that includes a small executive council, a plenary assembly in which all members are represented and that plays a role similar to that of a parliament, a secretariat that performs the day to day administrative activities of the organization, subsidiary organs that perform special functions and report to the executive council or the parliament, and sometimes a court or tribunal. They can be classified by their geographical reach and their function, e.g., human rights or development. The UN, for example, has a general global responsibility. But there are other organizations that have specific global responsibilities such as the World Bank Group or the Food and Agriculture Organization. There are also regional organizations with general and specific responsibilities such as the Organization of American States, the African Union or the Andean Community.