He is most famous for his theory of relativity, which revolutionized our understanding of space, time, gravity, and the universe. This theory encompasses both special relativity (dealing with objects moving at high speeds) and general relativity (dealing with gravity as a curvature of spacetime).

However, Einstein also made significant contributions to other areas of physics, including:

* Quantum mechanics: He contributed to the development of this theory, particularly in the area of the photoelectric effect.

* Statistical mechanics: He made significant contributions to understanding the behavior of atoms and molecules.

* Cosmology: He made groundbreaking contributions to our understanding of the universe's expansion.

So, while physics is his primary area, his impact extended to several subfields within physics.