In order to work the Global Positioning System has to allow for the effects of Relativity. Special relativity tell us that moving clocks run slow, and general relativity tell us that clocks run faster higher in a gravitational field. These effects don't just cancel out general relativity wins out and time does indeed run faster up in orbit with the satellites. This video explains a reason why we have these effects explaining why time is so important not just in GPS navigation systems but in every aspect of our lives.
Year of the Toad
8 hours ago