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GPS satellites carry clocks that would drift, relative to clocks on the ground, if engineers ignored relativity. Special relativity and general relativity pull those clocks in opposite directions, and the general effect wins. Without a correction, the position your phone shows would wander by kilometers a day. The map in your pocket is a physics experiment that has to stay honest.

Satellite navigation only works because the clocks are corrected for relativity.

Relativity in the Global Positioning System · Neil Ashby, Living Reviews in Relativity · 2003 · Factapp