An aircraft is a machine that is able tofly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil,or in a few cases thedownward thrust from jet engines.
The human activity that surrounds aircraft is called aviation. Crewedaircraft are flown by an onboard pilot, but unmanned aerial vehicles may beremotely controlled or self-controlled by onboard computers. Aircraft may be classified by different criteria, such as lift type, aircraft propulsion, usage and others.
Flying model craft and stories of manned flight go back many centuries, however the first manned ascent – and safe descent – in modern times took place by larger hot-air balloons developed in the 18th century. Each of the two World Wars led to great technical advances. Consequently, the history of aircraft can be divided into five eras:
Pioneers of flight, from the earliest experiments to 1914.First World War, 1914 to 1918.Aviation between the World Wars, 1918 to 1939.Second World War, 1939 to 1945.Postwar era, also called the jet age, 1945 to the present day.