An aircraft stabilizer is an aerodynamic surface, typically including one or more movable control surfaces, that provides longitudinal (pitch) and/or directional (yaw) stability and control. A stabilizer can feature a fixed or adjustable structure on which any movable control surfaces are hinged, or it can itself be a fully movable surface such as a stabilator. Depending on the context, "stabilizer" may sometimes describe only the front part of the overall surface.
In the conventional aircraft configuration, separate vertical (fin) and horizontal (tailplane) stabilizers form an empennage positioned at the tail of the aircraft. Other arrangements of the empennage, such as the V-tail configuration, feature stabilizers which contribute to a combination of longitudinal and directional stabilization and control.
Longitudinal stability and control may be obtained with other wing configurations, including canard, tandem wing and tailless aircraft.
Some types of aircraft are stabilized with electronic flight control; in this case, fixed and movable surfaces located anywhere along the aircraft may serve as active motion dampers or stabilizers.