British Airways plc (BA) is the flag carrier of the United Kingdom. It is headquartered in London, England at Waterside, near its main hub at Heathrow Airport.

The airline is the second largest UK-based carrier, based on fleet size and passengers carried, behind easyJet. In January 2011, BA merged with Iberia, creating the International Airlines Group (IAG), a holding company registered in Madrid, Spain. British Airways is the first passenger airline to have generated more than US$1 billion on a single air route in a year.

In 1972 a British Airways Board was established by the Government of the United Kingdom to manage the two nationalised airline corporations, British Overseas Airways Corporation and British European Airways, and two regional airlines, Cambrian Airways and Northeast Airlines. On 31 March 1974, all four companies were merged to form British Airways. BA was privatised in February 1987 as part of a wider privatisation plan by the Thatcher government. The carrier expanded with the acquisition of British Caledonian in 1987, Dan-Air in 1992, TAT European Airlines in 1993 and British Midland International in 2012.

The company continues to receive ample public support. British Airways received a bailout equivalent to £300 million. After the bailout, and receipt of government funding through the UK's furlough scheme, the airline received an additional £2 billion state backed loan in 2021.

The corporate lineage of British Airways goes back to five airlines established in the United Kingdom between 1916 and 1922. The first of these, Aircraft Transport & Travel (AT&T), began the world's first daily international commercial air service from London to Paris on 25 August 1919. The five airlines merged in 1924 and several other airlines were established and merged during the 1930s and 1940s. The mergers and acquisitions resulted in two state-owned airlines, the British Overseas Airways Corporation (BOAC), formed in 1939, and British European Airways (BEA), formed in 1947.

Proposals to establish a single British airline, combining the assets of the BOAC and BEA, were first raised in 1953 as a result of difficulties in attempts by BOAC and BEA to negotiate air rights through the British colony of Cyprus. Increasingly BOAC was protesting that BEA was using its subsidiary Cyprus Airways to circumvent an agreement that BEA would not fly routes further east than Cyprus, particularly to the increasingly important oil regions in the Middle East. The chairman of BOAC, Miles Thomas, was in favour of a merger as a potential solution to this disagreement and had backing for the idea from the Chancellor of the Exchequer at the time, Rab Butler. However, opposition from the Treasury blocked the proposal.

Consequently, it was only following the recommendations of the 1969 Edwards Report that a new British Airways Board, managing both BEA and BOAC, and the two regional British airlines Cambrian Airways based at Cardiff, and Northeast Airlines based at Newcastle upon Tyne, was constituted on 1 April 1972. Although each airline's branding was maintained initially, two years later the British Airways Board unified its branding, effectively establishing British Airways as an airline on 31 March 1974.

Following two years of fierce competition with British Caledonian, the second-largest airline in the United Kingdom at the time, the Government changed its aviation policy in 1976 so that the two carriers would no longer compete on long-haul routes.