An international organization (intergovernmental organization) is an organization established by a treaty or other instrument governed by international law and possessing its own international legal personality, such as the United Nations, the World Health Organization and NATO. International organizations are composed of primarily Member states, but may also include other entities, such as other international organizations. Additionally, entities (including, but not limited to states) may hold observer status.
Notable examples include the United Nations (UN), Organization for Security and Co-operation in Europe (OSCE), Council of Europe (COE), International Labour Organization (ILO) and International Police Organization (INTERPOL).
The first and oldest intergovernmental organization - being established by means of a treaty, and creating a permanent secretariat - is the International Telecommunication Union (founded in 1865). The first general international organization—addressing a variety of issues—was the League of Nations. The United Nations followed this model after World War II.