IATA vs ICAO Airport Codes: A Beginner Guide
IATA assigns 3-letter codes used on tickets, baggage tags and air waybills — for example LHR for London Heathrow and JFK for New York JFK.
ICAO assigns 4-letter codes used in flight planning and ATC, such as EGLL for Heathrow. The first letters indicate region and country.
A city code may cover multiple airports. Always confirm the exact airport code before booking or shipping.