The theory of relativity was developed by Albert Einstein, fundamentally changing the perception of time and space. Introduced in the early 20th century, the theory consists of two parts: the special theory of relativity and the general theory of relativity. It postulates that time and space are interwoven and that the laws of physics are the same for all non-accelerating observers. This groundbreaking work led to significant advancements in theoretical physics, impacting areas like cosmology and our understanding of gravity.