Coordinate system - Definition and Example

A coordinate system refers to two number lines that intersect at right angles. The figure below shows the coordinate system. 

Because the x-axis and the y-axis lie on a plane, we can also call the coordinate system a coordinate plane.

Why do we need a coordinate system?

The main purpose of a coordinate system is to locate points. Once you know how to locate points, you could also use the coordinate plane to graph lines, quadratic equations, and so forth ...