The International Civil Aviation Organization (ICAO, eye-KAY-oh) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international air transport to ensure safe and orderly growth. ICAO headquarters are located in the Quartier International of Montreal, Quebec, Canada.

The ICAO Council adopts standards and recommended practices concerning air navigation, its infrastructure, flight inspection, prevention of unlawful interference, and facilitation of border-crossing procedures for international civil aviation. ICAO defines the protocols for air accident investigation that are followed by transport safety authorities in countries signatory to the Chicago Convention on International Civil Aviation.

The Air Navigation Commission (ANC) is the technical body within ICAO. The commission is composed of 19 commissioners, nominated by the ICAO's contracting states and appointed by the ICAO Council. Commissioners serve as independent experts, who although nominated by their states, do not serve as state or political representatives. International Standards and Recommended Practices are developed under the direction of the ANC through the formal process of ICAO Panels. Once approved by the commission, standards are sent to the council, the political body of ICAO, for consultation and coordination with the member states before final adoption.

ICAO is distinct from other international air transport organizations, particularly because it alone is vested with international authority (among signatory states): other organizations include the International Air Transport Association (IATA), a trade association representing airlines; the Civil Air Navigation Services Organization (CANSO), an organization for Air navigation service providers (ANSPs); and the Airports Council International, a trade association of airport authorities.