**Spacetime** is any mathematical model that fuses the three dimensions of space (length, width, and depth) and the one dimension of time into a single four-dimensional manifold. It represents the “stage” in which physical phenomena take place.

Spacetime is a physical concept that combines our classic traditionally distinct notions of space and time into a single homogeneous entity. The introduction of spacetime is a direct consequence of the special theory of relativity, which establishes an equivalence between space and time.