An aileron is a movable surface located on the wings of an aircraft. It helps control the plane's roll, allowing it to tilt to the left or right during flight. When a pilot moves the control stick or yoke, the ailerons adjust their position, creating differences in lift between the wings. Ailerons work in pairs, with one wing's aileron moving up while the other moves down. This movement causes the aircraft to rotate around its longitudinal axis. Ailerons are essential for maneuverability and stability, making them a crucial component of an aircraft's control system, alongside other surfaces like elevators and rudders.