Cartesian Coordinates

Coordinate systems allow us to refer to points in space using numbers. There are different kinds of coordinate systems and they can have different numbers of dimensions. A very familiar coordinate system is the 2-D Cartesian coordinate system.
In this coordinate system two numbers, x and y, specify a point in a plane. The name Cartesian comes from Descartes who is said to have "invented" the system while laying in bed sick and watching a fly crawl across the tiled ceiling.

The above 2-D Cartesian system can be expanded into a 3-D cartesian if we simply add a third dimension, z. As x determines the left/right position and y determines the up/down position the additional coordinate z determines the back/forth position.