As mentioned earlier, the Global Positioning System (GPS) is now a part of a growing international context—the Global Navigation Satellite System (GNSS). One definition of GNSS embraces any constellation of satellites providing signals from space that facilitate autonomous positioning, navigation, and timing on a global scale. Currently, there are four systems that satisfy this definition. It is the Russian Federation’s GLONASS, European Union's GALILEO, China's BEIDOU and America's GPS.
There are several other regional satellite position, navigation and timing systems such as the Indian Regional Navigation Satellite System (IRNSS) and the Japanese Quasi-Zenith Satellite System (QZSS).