Currently, the GPS unit can directly show the WGS-84 geodetic coordinates (longitude, latitude, height) by analyzing the signal from a series of satellites. It originates from military use but has started its civil services now. Many airplanes, ships and trucks have already been equipped with GPS units which can help them locate their current locations and destinations, and measure their moving speeds. Some explorers, hikers and hunters are using GPS units too. The price of a GPS unit has dropped from thousands dollars to hundreds dollars and its weight and volume have decreased significantly too. A hand-held GPS unit may weigh less than a kilo, is as small as a wallet and costs only several hundred dollars, but can tell the universal coordinates of a location with an error less than 100 meters. The trend of the GPS unit development has shown that in a near future, it will be even cheaper and smaller and may become a necessary tool of everybody to tell the location like a watch to tell the time.

However, there is a problem for GPS users that the geodetic coordinates are very difficult to be directly related to a geographic location represented by its common name and a destination expressed by its common address. For example, if an individual takes a taxi equipped with a GPS unit to go to an unfamiliar address, the GPS unit will not help the driver if he/she is not given the geographic coordinates. The geographic coordinates expressed by long character strings of longitude and latitude are really difficult for people to remember and use.

But the Natural Area Code of an address can help. It is short and logic which has all the functions of any other global geodetic coordinates and can be easily obtained, remembered and used, and can become a necessary part of an address. Once people want to use a GPS unit to navigate to a destination expressed by its NAC, their GPS unit may directly show the distance from the current location to the destination and its relative orientation.

The destination can also be easily marked on a map with the NAC grid, which makes a NAC navigation system user easily draws the starting point, the path of the trip and the destination point on a map of the NAC grid or a digital map with the NAC grid in a computer before the trip. The user can also draw the actual path on the map during the trip and make the analysis after the trip.