Albert Einstein was a German-born theoretical physicist known for developing the theory of relativity, one of the two pillars of modern physics. He was awarded the Nobel Prize in Physics in 1921 for his discovery of the law of the photoelectric effect. Einstein's work revolutionized the field of physics with his general theory of relativity, which explained the phenomenon of gravity and its relation to spacetime. His contributions to science have had a profound impact on our understanding of the universe.