A satellite navigation or satnav system is a way of pinpointing position very exactly.
Satnav uses a system of satellites. The system gives exact positioning. It allows small electronic receivers to find their position (longitude, latitude, and altitude/elevation). The position is given within a few metres using time signals transmitted along a straight line (line of sight) by radio from satellites. The signals also allow the electronic receivers to calculate the current local time to high precision, which allows time synchronisation. A satellite navigation system with global coverage may be called a global navigation satellite system (GNSS).
Satellite navigation Facts for Kids. Kiddle Encyclopedia.