Heathrow Airport originally called London Airport until 1966 and now known as London Heathrow (IATA: LHR, ICAO: EGLL), is a major international airport in London, England. With Gatwick, City, Luton, Stansted and Southend, it is one of six international airports serving London. The airport facility is owned and operated by Heathrow Airport Holdings. In 2020, it was the third busiest airport in the world by international passenger traffic, the twenty-second busiest airport in the world by total passenger traffic, and the third busiest airport in Europe by passenger traffic.

Heathrow was founded as a small airfield in 1929 but was developed into a much larger airport after World War Two. The airport, which lies 14 miles (23 km) west of Central London on a site that covers 12.27 square kilometres (4.74 sq mi), gradually expanded over the next seventy-five years, and now has two parallel east-west runways along with four operational passenger terminals, and one cargo terminal. The airport is the primary hub for British Airways and the primary operating base for Virgin Atlantic; in 2020, it handled 22.1 million passengers, a 72.4% drop from 2019, as well as 207,070 aircraft movements.

Heathrow is 14 mi (23 km) west of central London. It is located 3 mi (4.8 km) west of the town of Hounslow, 3 miles south of Hayes, and 3 miles northeast of Staines-upon-Thames.

The airport is surrounded by the villages of Sipson, Harlington, Harmondsworth, and Longford to the north and the neighbourhoods of Cranford and Hatton to the east. To the south lie Feltham, Bedfont and Stanwell while to the west Heathrow is separated from Wraysbury, Horton and Windsor in Berkshire by the M25 motorway. Heathrow falls entirely within the boundaries of the London Borough of Hillingdon, and under the Twickenham postcode area, with the postcode TW6. The airport is located within the Hayes and Harlington parliamentary constituency.

As the airport is located west of London and as its runways run east-west, an airliner’s landing approach is usually directly over the conurbation of London when the wind is from the west, which is most of the time.