The point mass, also known as a particle, is a simple model representation of a body. It is primarily used to facilitate the description of the body’s motion. Properties of the body such as volume and shape are neglected. The body is considered as a mathematical point that has no extension, but possesses a finite mass. The entire mass of the body is localized at this point. Typically, one would choose the center of gravity of the body as this point. In this chapter, you will learn how to describe the movement of bodies under these simplifications. We will introduce velocity and acceleration as key quantities in this process.