From SKYbrary Wiki
GALILEO is a European Satellite Navigation System.
More and more often, it will become necessary to ascertain one's precise position in space and time in a reliable manner. This will be possible with the GALILEO satellite radio navigation system, an initiative launched by the European Union and the European Space Agency. This worldwide system will ensure complementarity with the US Global Positioning System (GPS) system.
Satellite radio navigation is an advanced technology. It is based on the emission from satellites of signals indicating the time extremely precisely. When the signals from several of the GALILEO satellites are utilised simultaneously, this enables any individual to determine his or her position or the location of any moving or stationary object (e.g. a vehicle, a ship, or a herd of cattle, etc.) to within one metre thanks to a small cheap individual receiver.
GALILEO is based on a constellation of 30 satellites and ground stations providing information concerning the positioning of users in many sectors such as transport (vehicle location, route searching, speed control, guidance systems, etc.), social services (e.g. aid for the disabled or elderly), the justice system and customs services (location of suspects, border controls), public works (geographical information systems), search and rescue systems, or leisure (direction-finding at sea or in the mountains, etc.).
For more information refer to Navipedia.