Answer:
The uniformity in the speed of light in all frame of references and for all the observers.
Step-by-step explanation:
The theory of special relativity throws light on the link between space and time in inertial frame.
Time dilation is when the object moves with relativistic speed the time slows down an similar is the case with length contraction, the length is shortened or contracts when the body moves with relativistic speed.
The main idea behind these is that the speed at which the light travels is the same in all the frame of reference and for all the observers.