Time Dilation is a theory of special relativity, where there exists a unique difference in the elapsed time measured by two observers, either due to a velocity difference relative to each other, or by being differently situated relative to a gravitational field. In very simple words, a moving clock runs more slowly when viewed by a frame of reference that is not in motion with it. The clock was found to be slower by exactly the amount Einstein's equations predicted.
A notion of simultaneity is required in order to make a comparison of the rates of clocks carried by the two observers. If the first observer’s notion of simultaneity is used, it is found that the second observer’s clock runs slower than the first observer’s by a factor of Square root of? (1-v2/c2), where v is the relative velocity of the observers and c equals the speed of light.
Here at MathsOne, one of The Best Maths Tuition Centres in Kerala we educate our students in the fundamentals of the time-space continuum.