airport also called air terminal, aerodrome , or airfield

The requirements for airports have increased in complexity and scale since the earliest days of flying. Before World War II the landing and takeoff distance of most passenger-transport aircraft was at most 600 metres (2,000 feet). Additional clear areas were provided for blind landings or bad-weather runs, but the total area involved rarely exceeded 500 acres (200 hectares).

It was not until the general introduction of heavy monoplanes for transport, such as the Douglas DC-3, during the late 1930s that extensive takeoff and landing distances were needed. Even then, the prewar airfields at New York City (La Guardia), London (Croydon), Paris (Le Bourget), and Berlin (Tempelhof) were laid out on sites close to the city centres. Because even transport aircraft of the period were relatively light, paved runways were a rarity. Croydon, Tempelhof, and Le Bourget, for example, all operated from grass strips only. Early airports were also major centres of leisure activity, often attracting more visitors than passengers. In 1939 La Guardia Airport attracted almost 250,000 visitors per month, reaching a peak of 7,000 in one day, compared with a maximum daily throughput of only 3,000 passengers. In 1929 Berlin’s airport reported 750,000 visitors and boasted a restaurant that could seat 3,000 people on the roof of the passenger terminal. The status of prewar airports as major social centres was reflected in their design, especially where the requirements of catering, observation decks, and parking were paramount. Indeed, the requirements of aircraft and passengers were not at all dominant at early airfields.

Much long-distance air transport was handled by the large seaplanes known as flying boats or clippers. These aircraft, though slow and of limited range, offered a level of comfort that was necessary for long-distance travel. Air terminal facilities were necessarily constructed close to large open stretches of water. La Guardia Airport and Santos Dumont Airport in Rio de Janeiro are examples of airports that still operate on sites originally chosen for their ability to handle large seaplanes. The large facilities at Southampton Water in the United Kingdom have now disappeared, but the artificial lake at Linate Airport near Milan, Italy, is still to be found close to the present administration facilities.

The vast majority of airfields throughout the world are still relatively simple facilities. Even now, many have unpaved runways or at most lightly paved runways with tiny terminal or administration buildings, a rudimentary control tower, and crude landing aids. Such facilities can deal only with light aircraft and a negligible flow of passengers or freight. Heavy air traffic, on the other hand, is now almost entirely handled by sophisticated airport facilities that can accommodate the needs of crew, passengers, and freight and the great range of aircraft types that have evolved to meet the needs of modern air transport and general aviation.

More than 100 airports around the world now handle at least 10 million passengers each per year; nearly half of these are in the United States. Dozens of airports regularly move more than 30 million passengers on a yearly basis—Chicago’s O’Hare International Airport and the Hartsfield Atlanta International Airport in Georgia each handle more than 75 million. The Memphis (Tennessee) International Airport, the home airport of the FedEx Corporation’s cargo service, and the Hong Kong International Airport are the world’s largest cargo shippers, each of which handled nearly four million tons in 2007. In order to meet the increasing demand for air travel, large transport aircraft powered by multiple jet and turboprop engines have been built. Such aircraft require extensive ground facilities, runways, taxiways, fire-fighting and rescue services, passenger- and cargo-handling facilities, access to car parking and public transport, lighting, navigational and approach aids, and various support facilities such as catering, meteorology, and governmental inspection. In order to be attractively convenient, the complex of activities and facilities that make up a modern airport must be located sufficiently close to the main centres of world population. At the same time, they must be adequately distant, so that the environmental problems associated with the noise of large aircraft and the activities of large numbers of passengers, workers, and visitors do not become intolerable to the cities that are served.