Fly-by-wire describes a system where no directly connection of the stearing
instuments of an aircraft to the aerodynamicly acting flaps exists.
In smaller or older planes the pilot drives the flaps via steel wire
directly, this needs much of musculair strength in case of bigger or faster
planes.
In a fly-by-wire system the stearing command, given by the pilot, is converted
into an electronic signal, this signal is transfered over wires to a servo that
drives the flaps.