Chicago O'Hare International Airport is a major international airport serving Chicago, Illinois, located on the city's Northwest Side, approximately 17 miles (27 km) northwest of the Loop business district. Operated by the Chicago Department of Aviation and covering 7,627 acres (3,087 ha), O'Hare has non-stop flights to 214 destinations in North America, South America, the Caribbean, Europe, Africa, Asia, the Middle East, Oceania, and the North Atlantic region as of November 2022. As of 2023, O'Hare is considered the world's most connected airport. It is also U.S.A.'s 4th busiest airport, and 7th biggest airport.

An IATA airport code, also known as an IATA location identifier, IATA station code, or simply a location identifier, is a three-letter geocode designating many airports and metropolitan areas around the world, defined by the International Air Transport Association (IATA). The characters prominently displayed on baggage tags attached at airport check-in desks are an example of a way these codes are used.