Coordinate system by which the position or location of any place on the Earth's surface can be determined and described.
Latitude is a measurement of location north or south of the Equator. Lines of latitude are known as parallels, or parallels of latitude. Longitude is a measurement of location east or west of the prime meridian, which passes through Greenwich, Eng. The combination of meridians of longitude and parallels of latitude establishes a grid by which exact positions can be determined: for example, a point described as 40k N, 30k W is located 40k of arc north of the Equator and 30k of arc west of the Greenwich meridian.