He developed two theories of relativity:

* Special Relativity: Published in 1905, it deals with the relationship between space and time and the idea that the laws of physics are the same for all observers in uniform motion.

* General Relativity: Published in 1915, it extends special relativity to include gravity, describing it as a curvature of spacetime caused by mass and energy.

While other scientists contributed to the understanding of space, time, and gravity before Einstein, his theories revolutionized our understanding of these fundamental concepts and are widely considered his most significant contribution to physics.