The International Air Transport Association (IATA) is a trade association of the world’s airlines. Consisting of 290 airlines, primarily major carriers, representing 117 countries, the IATA's member airlines account for carrying approximately 82% of total Available Seat Miles air traffic IATA supports airline activity and helps formulate industry policy and standards. It is headquartered in Montreal, Quebec, Canada with Executive Offices in Geneva, Switzerland.

IATA was formed in April 1945 in Havana, Cuba. It is the successor to the International Air Traffic Association, which was formed in 1919 at The Hague, Netherlands. At its founding, IATA consisted of 57 airlines from 31 countries. Much of IATA’s early work was technical and it provided input to the newly created International Civil Aviation Organization (ICAO), which was reflected in the annexes of the Chicago Convention, the international treaty that still governs the conduct of international air transport today.

The Chicago Convention couldn’t resolve the issue of who flies where, however, and this has resulted in the thousands of bilateral air transport agreements in existence today. The benchmark standard for the early bilaterals was the 1946 United States-United Kingdom Bermuda Agreement.

At a time when many airlines were government owned and loss-making, IATA operated as a cartel, charged by the governments with setting a fixed fare structure that avoided price competition. The first Traffic Conference was held in 1947 in Rio de Janeiro and reached unanimous agreement on some 400 resolutions.

The International Air Transport Association uses sets of 3-letter IATA identifiers which are used for airline operations, baggage routing, and ticketing. There is no specific organization scheme to IATA identifiers; typically they take on the abbreviation of the airport or city such as MNL for Manila Ninoy Aquino Airport.

In the United States, the IATA identifier usually equals the FAA identifier, but this is not always the case. A prominent example is Sawyer International Airport, Michigan, which uses the FAA identifier SAW and the IATA identifier MQT. The assignment of these codes is governed by IATA Resolution 763, and it is administered by IATA headquarters in Montreal. The codes are published semiannually in the IATA Airline Coding Directory.