Albert Einstein is famous for the theory of general relativity, which he published in 1915. This groundbreaking theory redefined how we understand gravity, explaining it as the curvature of space-time caused by mass. Prior to this, gravity was viewed merely as a force acting at a distance. Einstein's work provided a deeper understanding of the universe, leading to predictions about the bending of light around massive objects, the expansion of the universe, and black holes. General relativity has been confirmed through numerous experiments and observations over the years, solidifying Einstein's legacy as one of the most influential physicists in history.