In this talk we will survey the development of the Green's function for the Boltzmann equation. The talk will include the motivation from the field of hyperbolic conservation laws, the connection between the Boltzmann equation and the hyperbolic conservation laws, and the particle-like and the wave-like duality in the Boltzmann equation. With all these components one can realize a clear layout of the Green's function for the Boltzmann equation. Finally we will present the application of the Green's function to an initial-boundary value problem in the half space domain.