A ngular momentum - a property associated with any particle or system which is undergoing circular motion. These motions produce orbital angular momentum and spin angular momentum, respectively. The following describes the important characteristics of angular momentum.
Angular momentum is a vector quantity, i.e it has magnitude and direction.
The direction of the angular momentum vector is at right angles to the plane defined by the circular motion of the particle. The magnitude of the angular momentum also increases with the radius of the circular motion. Like energy, angular momentum in quantum mechanics is quantized - it can only increase or decrease by fixed amounts or quanta.