An IGO, or intergovernmental organization, is an organization composed primarily of sovereign states or other intergovernmental organizations. IGOs are established by treaty or other agreement that acts as a charter creating the organization. They are involved in treaty making and can enter into agreements with other IGOs or with states. IGOs have international legal status that may include privileges, immunities, rights, and duties that are based upon their founding charter or statute. IGOs usually have a governing structure that includes a small executive council, a plenary assembly, a secretariat, and subsidiary organs that perform special functions and report to the executive council or the plenary assembly. IGOs may focus on trade, security, international crime, or other issues. Examples of IGOs include the United Nations, the African Union, NATO, and Interpol.