Here I was talking about General Relativity as its effect is much bigger than that of Special Relativity in this case, but both General and Special Relativity have much to do with the implementation of our GPS system. The clocks in the GPS satellites are corrected for the effects of time moving faster due to them being further away from Earth (general relativity) and slower due to time dilation from their moving at high speed (special relativity), as compared to the perspective of a clock on earth.