Scattering refers to a broad class of phenomena in which waves or particles are deflected (that is, they change change their trajectory) due to the collision with other particles (or waves, from a quantum point of view). There deflection occurs in a disorderly and largely random manner (scattering can be translated as “scattering”), and for this the diffusion differs from reflection and refraction, which change trajectories in a regular and determined manner. They are considered processes of scattering only the elastic or nearly elastic interactions, which ie not do not involve significant energy sales or gains.