Which of these is a part of an airplane wing?
Ailerons are moving surfaces usually placed near the tips of the wings. The function of the aileron is simple, by moving upwards or downwards it modifies the angle of attack of that section of the wing, sinking or lifting it. This change in the aerodynamic is due to the modification of the relative curve of the airfoil. Note that ailerons are complementary, so if one moves the other will move on the other direction in the same proportion. This improves the effect as one wing is lifted and the other sunk. Ailerons control the X-axis or roll movement of the aircraft.
Ailerons are controlled by the pilot from the cockpit, with the lateral axis of the joystick. To make coordinated turns the movement must be combined with the rudder in the same direction. In some planes ailerons are just divided elevators, being possible to use the same surface as aileron or elevator (delta-wing airplanes).