Einstein's Theory of Relativity consists of two parts: the Special Theory of Relativity and the General Theory of Relativity. The Special Theory, introduced in 1905, revolutionized our understanding of space and time, showing that they are interconnected and relative to the observer's speed. It also established the famous equation E=mc², which describes the equivalence of mass and energy. The General Theory of Relativity, published in 1915, expanded these ideas to include gravity. It proposed that massive objects like Earth and the Sun warp the fabric of space-time, causing other objects to move along curved paths. This theory has been confirmed through various experiments and observations, including the bending of light around massive bodies.