Vertical stabilizer

static part of the vertical tail of an aircraft, often with movable (side) rudders hinged to it to provide control, stability and trim in yaw

A vertical stabilizer or a tail fin is a part of the vertical tail of an airplane (a kind of aircraft). They also usually have one or more moveable rudders hinged to it. The role of a vertical stabilizer is to make the aircraft stable, give the pilots control of the aircraft and control the yaw of the aircraft. A vertical stabilizer is normally place on the rear fuselage of the aircraft. One plane crash involving the vertical stabilizer is Japan Airlines Flight 123.