Coordinates are numbers which describe the location of points in a plane or in space. For example, the height above sea level is a coordinate which is useful for describing points near the surface of the earth.

For more, visit the Wikipedia entry for coordinates, URL: http://en.wikipedia.org/wiki/Coordinates_(mathematics)

For more, visit the Wikipedia entry for geographic coordinate system, URL: http://en.wikipedia.org/wiki/Geographic_coordinate_system