The Cartesian plane is composed of two perpendicular axes. Their intersection defines the origin of the plane. Each axis is graduated starting from the origin.

- The horizontal axis is the abscissa axis (also known as the "x axis"),
- The vertical axis is the ordinate axis (also known as the "y axis").

These axes divide the cartesian plane into four quadrants.

A point is located in the Cartesian plane by its abscissa "x" and its ordinate "y". Together in this order, (x , y) constitutes the coordinates of the point.