A system to locate points using assigned numbers or coordinates is called a coordinate system. The Cartesian coordinate system is the simplest coordinate system in which coordinate axes are mutually perpendicular and equally scaled. In this system, coordinates of a point P are defined by the length of segments on the coordinate axes denoted by (x, y, z). A position of a point in this system is specified by assigning real numbers to x, y, and z (Figure 1).

Figure 1. Cartesian coordinate system.

By convention, three-dimensional Cartesian coordinate system can be right- or left-handed depending on the axis chosen to represent the direction of the x and y coordinates.