The Global Positioning System (GPS) is a satellite based utility that is designed to provide end user of the system with positioning services, navigation services, and timing abbreviate as (PNT).
GPS consists of three main blocks two of which are supported and owned by US Government (Air Force Military Branch). These blocks are space and control. The end user block is commercialized and ordinary people can use it for various applications, such as business, recreational and educational.
GPS is operating 24 medium orbit satellites which transmit signals to earth. This signal is 1-way signal and contains location of each satellite in relation to earth and the GPS receiver. Entire operation of GPS satellites is a part of space block or GPS system.
Control is used primary to maneuver satellites into proper position on the orbit its also responsible for adjusting a clock with is running faster due to high speeds that is explained to us by Einstein in his Relativity Theory.
User block of the GPS system is not overseen by the US Government and is supported mainly by the privet enterprise. Many GPS equipment companies are part of this user block of the GPS system.
GSP system was initially designed to support US Military but later on opened up to public once government realized economical potential of the system. Moreover, it is open to world wide public. Many countries are using it for multiple purposes and many companies were established as a result that build user devices commonly called GPS receivers.