Theories of Relativity, developed by Albert Einstein, consist of two main parts: Special Relativity and General Relativity. Special Relativity, introduced in 1905, focuses on the physics of objects moving at constant speeds, particularly at speeds close to that of light. It reveals that time and space are interconnected, leading to the famous equation E=mc², which shows the equivalence of energy and mass. General Relativity, published in 1915, expands on this by incorporating gravity. It describes gravity not as a force but as a curvature of spacetime caused by mass. This theory has been confirmed through various experiments and observations, such as the bending of light around massive objects.