John Milnor is an American mathematician known for his significant contributions to topology, differential geometry, and dynamical systems. Born on February 20, 1931, he has received numerous awards, including the prestigious Fields Medal in 1962 for his work on the differential topology of manifolds. Milnor is particularly famous for his discovery of exotic spheres, which are smooth manifolds that are homeomorphic but not diffeomorphic to the standard n-dimensional sphere. His research has greatly influenced the fields of mathematics and theoretical physics, making him a prominent figure in modern mathematics.