Refer to figure.
The rudder is also a controllable flap hinged to the fin or the vertical stabilizer. The rudder is controlled by the rudder pedals which are moved by the feet of the pilot. When the right pedal is depressed, the rudder moves to the right, causing a force to be generated on the left side of the fin. This force acts through the CG, making the aircraft nose move sideways through the vertical axis. The same thing happens when the left pedal is pressed. However, in this case, the nose moves to the left. This motion is known as a yaw motion.