Is time an illusion?

Einstein baffles us asserting "time" is not running at the same rate everywhere. Einstein mathematics show that the time given by a clock depends on that clock relative motion with respect to an observer. This phenomenon called "time dilation" amounts to the alteration of "time" with motion. There is also gravity-time-dilation. Einstein's prediction made in the early 20th century has been verified experimentally by Hafele and Keating in 1971 and confirmed over and over since. The experiments consisted of identical atomic clocks, some flying in planes around the globe and a reference clock left on the ground playing the role of the observer; the time differences coincided precisely to Einstein's calculations!