In this paper we demonstrate that the “pure” spacetime and electromagnetic spacetime are bound together. The “pure” spacetime and electromagnetic spacetime all behave as the wave in character and furthermore, both of them change at the same speed. Based on the understanding of the “pure” spacetime and electromagnetic spacetime, we give out the reasonable explanation why the speed of light keeps constant and how the gravity is created among the matters. In addition, some practical applications of the concepts developed in this work are proposed.