Theory of Flight - Primary Flight Controls
Ailerons are the outboard flight controls on the trailing edge of the wings. These control the aircraft along the longitudinal axis and provide aircraft roll capability.
The are usually placed at the rear of the aircraft, on the tailplane. Although the elevators can be moved and even removed on some aircraft, they are most commonly found on the tail plane, especially in commercial aircraft. The elevators control the aircraft along the lateral axis and provides pitch control.
The rudder is always placed on the tailplane and control the aircraft using the normal axis by yawing the aircraft.