The key concept behind the theory of relativity is that the laws of physics are the same for all observers, regardless of their relative motion. Proposed by Albert Einstein, this theory revolutionized the understanding of space and time. It encompasses two main components: special relativity, which deals with objects moving at constant speed, and general relativity, which addresses gravitational effects on spacetime. This framework helps explain how mass and energy affect the curvature of space, influencing phenomena such as gravitational lensing and time dilation, altering how we perceive the universe.