GPS is one of several global navigation systems. The Soviets had GLONASS (24 satellites) and China has BeiDou (33 satellites).
The European Union has Galileo (22 satellites operational).
Our USA system is the GPS system we are all so familiar with (31 satellites). BTW it is over 40 years old, so it you struggle to imagine a non-GPS world it is understandable, as a good portion of the population is too young to have experienced a non-GPS environment unless they had traveled while young.
Several of these Global Navigation Systems “cooperate” in that Global Navigation Systems Receivers are offered that use several of the different signals at the same time.
All well and good, until it doesn’t work.