Spin in Quantum Theory*

Discovery of spin degrees of freedom in quantum physics was an imporant milestone in 20th century science. Just like mass, spin is an intrinsic property of elementary/composite particles which detemines fundamental forms of the matter world. In this talk, I will review some of the revolutionary ideas and concepts, and fascinating phenomena that spin brought in. The role of spin in the broad areas of quantum physics inlcuding AMO, condensed matter, nuclear and particle physics, as well as "theory of everything" will be discussed