In elementary plane geometry a point is described by given it a name, such as P, Q or R. But in coordinate geometry, a point is described by its position in the plane. The position of a point is given by an ordered pair (a, b) of real numbers. The credit for introducing point as an ordered pair of real numbers goes to the French mathematician René Descartes (1596 – 1650).
There are many different ways of associating an ordered pair of real numbers to a point. The simplest of them is rectangular Cartesian coordinate system.