The term "Cartesian" is used to refer to anything that derives from René Descartes' conception of geometry (1637), which is based on the representation of
points in the plane by ordered pairs of real numbers, the so-called Cartesian
coordinates. In this way, the plane is identified with
, which is a Cartesian
product of sets, Euclidean space is identified with , and so on.

Descartes' idea allows geometric relations to be expressed by means of algebraic equalities (Cartesian equations), giving rise to what is nowadays known as analytic
geometry.