Cartesian coordinates are a method to denote where a given point is on a given coordinate plane in terms of horizontal and vertical distance from the origin, (0,0). 

For example, the point (8,4) would be 8 units to the right of the origin and the 4 units up, and (-4,-6) would be 4 units left of the origin and then 6 units down.

Cartesian coordinates can be used any arbitrary number of dimensions.