Airport engineering involves planning, designing, and constructing terminals, runways, and navigation aids to facilitate passenger and freight air transportation. An airport provides a connection between ground transportation and air transportation via an airfield, an area where aircraft can take off and land with optional navigational markings. The development of aviation has progressed from early experimental flights in the early 1900s to modern international networks and large passenger aircraft, regulated through organizations like ICAO. In India, air transportation has grown from early mail flights in 1911 to a system today managed under the Airport Authority of India, which controls air traffic and develops airports nationwide.