One of the ways that we measure motion is by an object's velocity. Velocity is the measure of the displacement of an object over time. The magnitude of the velocity is the speed of the object and does not include direction. The average velocity of an object is calculated by dividing the total displacement of the object by the time it took to complete that displacement.
A convenient way of representing motion is to use position versus time graphs, which display the motion in such a way that it is easy to see certain aspects of the motion. Since the slope of the position time graph is the velocity of the object, steeper portions of the graph represent greater velocities. The flat portions of the graph represent objects at rest and the slope of the line connecting the starting and ending points of the graph is the average velocity of the object.