Einstein's Theory of General Relativity is a scientific theory that explains how gravity works. Proposed by Albert Einstein in 1915, it describes gravity not as a force, but as a curvature of space and time caused by mass. This means that massive objects, like planets and stars, bend the fabric of space-time around them, influencing the movement of other objects. The theory also predicts phenomena such as the bending of light around massive objects and the existence of black holes. General Relativity has been confirmed through various experiments and observations, making it a cornerstone of modern physics and our understanding of the universe.