Yaw is a type of rotational movement of an aircraft or spacecraft about its vertical axis. It is the opposite of pitch, which is rotation about the aircraft or spacecraft's lateral axis, and roll, which is rotation about its longitudinal axis.
Yaw is typically controlled by the rudder on an aircraft, or by thrusters or other control surfaces on a spacecraft. It is used to steer the aircraft or spacecraft in the desired direction and to maintain its stability and orientation.
Overall, yaw is an important concept in the aerospace industry, and it plays a role in the design and operation of aircraft and spacecraft.