general relativity, n.Definitions

General Relativity is a Model of Everything that is different than the Standard Model in this: General Relativity is a theoretical approach to physics where gravity is the star of the show and everything else is acting as a backup singer, while the Standard Model is an approach the allows the other 3 non-gravitational forces to shine (photons, gluons, intermediate vector-bosons).

General Relativity is a theory of gravity that says space is curved, so the shortest path for a traveling photon is not straight, but curved depending on masses.

General Relativity is the idea that the speed of light is constant, so even if you're going at 99% the speed of light in the opposite direction and you shine a flashlight, the light comes out at the speed of light.