General relativity is a theory of gravity proposed by Albert Einstein. It describes gravity as the curvature of spacetime caused by mass and energy. In this theory, objects with mass or energy create curves in spacetime, and other objects move along these curves. It explains phenomena like the bending of light by gravity and the expansion of the universe. General relativity also suggests that time can be affected by gravity, causing it to pass more slowly near massive objects. Overall, it provides a framework for understanding gravity as the geometry of the universe in a concise mathematical formulation.