Abstract: A review of the historical background of origins of the special theory of relativity is given. Next it points out that by critically examinating the physical significance of the concepts of spatial and temporal intervals based on a careful definition of the simultaneity of distant events, Einstein discovered that the concept of a universal or absolute time, on which Newtonian mechanics and the Galilean transformations between the coordinates of two inertial frames of reference are based, has to be abandoned, and instead he put forward new concepts and laws of relative space and time and new kinematics for all of physics based on two postulates, the relativity principle and the principle of the constancy of the velocity of light. It indicates that Einstein＇s new kinematics is the foundation of all laws of physics which continue to preserve their invariance and symmetry in all of uniform motion, and also the foundation of the existence of the causality in all the natural phenomena. Finally, the major constributions of STR to physics are presented.

Key words: mechanics, electrodynamics, electron theory, STR （special theory of relativity）, time and space relative motion