Velocity is a physical vector quantity that describes the rate at which an object changes its position. It is defined as the displacement (change in position) of an object divided by the time interval during which the displacement occurs. Velocity is expressed in units of distance per unit time, such as meters per second (m/s) or kilometers per hour (km/h). Velocity takes into account both the speed and the direction of an object's motion. Speed, on the other hand, is a scalar quantity that only describes the rate of motion without regard to direction. Speed and velocity are therefore different concepts, and an object can have a high speed but low velocity if it is changing direction frequently. Velocity is an important concept in physics as it provides information about the motion of an object and its trajectory.