Albert Einstein's theory of relativity reshaped modern physics by introducing revolutionary concepts about the nature of space and time. His formulation of special relativity established that the laws of physics are the same for all non-accelerating observers and revealed the famous equation E=mc², linking energy and mass. Subsequently, the theory of general relativity described gravity as a curvature in spacetime, fundamentally altering our understanding of cosmic phenomena. These insights have influenced areas such as cosmology and technology, contributing to advancements in GPS systems and understanding the universe.