GPS devices, or Global Positioning System devices, use Satellites to pin point the position of that device.
With this information, and the maps the GPS device stores, a GPS device can be used to calculate the fastest or shortest route to any destination , in almost any country in the world.
A GPS installed in a vehicle is able to monitor the speed, the direction and the location of the vehicle. With this data, and the installed map, the GPS unit can direct a user to any destination in that country.
Modern GPS units are able to route by the shortest route or fastest route.
With the large amount of data the service provider receives from all their GPS units, they can calculate the least congested route at any time of the day, in any day of the week.
With LIVE services, the service providers can also show which roads are congested, and then direct drivers around accidents and heavy congestion - in real time.