roll is controlled by movable sections on the trailing edge of the wings called ailerons. the ailerons move in opposition to one another—one goes up as the other goes down. the difference in camber of the wing cause a difference in lift and thus a rolling movement. as well as ailerons, there are sometimes also spoilers—small hinged plates on the upper surface of the wing, originally used to produce drag to slow the aircraft down and to reduce lift when descending. on modern aircraft, which have the benefit of automation, they can be used in combination with the ailerons to provide roll control.