The BeiDou Navigation Satellite System is a Chinese system that provides satellite navigation services. It comprises two satellite constellations, with the first one, known as BeiDou-1, being launched in 2000 and decommissioned in 2012. The second generation, known as BeiDou-2 or COMPASS, became operational in China in 2011 and offered services to the Asia-Pacific region in 2012. In 2015, the third generation, BeiDou-3, was launched for global coverage, with the final satellite launched in June 2020. The system offers full global coverage for navigation and timing and is seen as an alternative to other satellite navigation systems like Russia’s GLONASS, the European Galileo positioning system, and the US’s GPS.