What is a GPS?

Many maps, such as road maps, only deal with the two-dimensional location of an object without taking into account its elevation.  While convenient, these maps do not accurately represent the surface of the earth.   The earth is contorted ("relief"), and because of this latitude, longitude and elevation are necessary to locate areas exactly on a map (three-points, or "triangulation" is required to accurately locate something within 3-Dimensional space).  Maps that deal with three dimensions are called topographic maps. Topographic maps take into account the elevation of the area being mapped above a ‘reference datum’, thus showing the actual shape of the area.

Photographs, satellite imagery, surface and subsurface scientific exploration and other means of gathering data have changed the way modern maps are constructed. Recent computer technologies have allowed for the development of Geographic Information Systems which provide complex pictures of the earth - both on the surface and beneath it.  The global address of any place on earth includes both latitude and longitude. This coordinate system is widely used in all areas of navigation and related technologies. An example is Global Positioning System technology which uses a receiver to transmit a signal to satellites orbiting the earth. The GPS unit then uses the amount of time it takes for the satellite to receive its signal, and the satellite's' position in the sky to calculate an exact latitude and longitude.

An internet site that can give you a set of latitude and longitude coordinates based on your geographic position.