Fly-by-wire (FBW) is a system that replaces an aircraft’s conventional manual flight controls with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires (hence the fly-by-wire term), and flight control computers determine how to move the actuators at each control surface to provide the ordered response.
The fly-by-wire system also allows automatic signals sent by the aircraft’s computers to perform functions without the pilot’s input, as in systems that automatically help stabilize the aircraft or prevent unsafe operation of the aircraft outside of its performance envelope.