The General Theory of Relativity, proposed by Albert Einstein in 1915, revolutionized our understanding of gravity. It describes gravity not as a force, but as a curvature of spacetime caused by mass. This means that massive objects like planets and stars warp the space around them, influencing the motion of other objects. This theory has profound implications for our understanding of the universe, including the behavior of light around massive bodies and the expansion of the universe itself. It has been confirmed through various experiments and observations, such as the bending of light during a solar eclipse.