An autogyro is a flying machine. Like a helicopter, it is a rotary wing aircraft- which means that it has a rotor to provide lift instead of wings like conventional airplanes. Unlike a helicopter, the rotor is not powered by the engine. It is made to spin by aerodynamic forces, through a phenomenon called autorotation. Since the rotor is not powered, an autogyro needs a separate source for propulsion, like an airplane. Conventionally, these have been propellers, but it's possible to use jet engines as well.