Book excerpt: Superlattices and Other Heterostructures deals with optical properties of superlattices and quantum-well structures with emphasis on phenomena governed by crystal symmetries. After a brief introduction to group theory and symmetries, methods to calculate spectra of electrons, excitions and phonons in heterostructures are discussed. Further chapters cover absorption and reflection of light under interband transitions, cyclotron and electron spin-resoncance, light scattering by free and bound carriers as well as by optical and acoustic phonons, polarized photoluminescence, optical spin orientation of electrons and excitions, and nonlinear optical and photogalvanic effects.