Angular displacement is a concept used in rotational motion to describe the change in the angular position or orientation of an object with respect to a reference point or axis. It measures the angle through which an object has rotated or the angle between the initial and final positions of the rotating object.

In linear motion, displacement is the change in position of an object along a straight line. Similarly, in rotational motion, angular displacement is the change in the angle of the object's position as it rotates about an axis.

Angular displacement is a vector quantity and is represented by the Greek letter theta (θ). The SI unit of angular displacement is the radian (rad). One radian is defined as the angle subtended at the center of a circle by an arc equal in length to the radius of the circle. Alternatively, angular displacement can also be measured in degrees (°), where one full revolution (one complete circle) is equivalent to 360°.