Kinematics

Kinematics is the study of a body's motion without concern to the forces that act upon it.

Displacement

A body's displacement is its change in position from some initial point of reference. Displacement is defined the difference between that body's current position $x$ and its initial position $x_0$, such that:

$$s=x-x_0$$

Where $s$ is the displacement of the body, which may also be expressed as $\Delta x$.