System whose rectilinear axes cross at the origin of the coordinates.

The coordinates of a point in a Cartesian system are called
Cartesian coordinates. If the axes are perpendicular, the coordinates of the points of the system are called
rectangular coordinates.
Properties
If the axes are perpendicular, the Cartesian system is orthogonal. If the axes have the same intervals and the same
norm, then the axes are said to be normalized, and the Cartesian system made up of these axes is normalized.
Example
This is a Cartesian system in which the axes are orthogonal but not normalized :

Therefore, this is not a Cartesian plane.