In a textbook for graduate or undergraduate students with some background in quantum physics, optics, and solid state physics, Solé, L. E. Bausá, and D. Jaque (all U. Autónoma de Madrid, Spain) explain the basic aspects of optical spectroscopy of solids needed to interpret simple optical spectra such as absorption, reflectivity, emission, and scattering. Optical spectroscopy refers to the range of interacting electromagnetic radiation lying within the range of visible light plus a small part of the ultraviolet and infrared regions. The solid materials considered include metals, semiconductors, and insulators, and though the focus is on the spectroscopy of centers embedded in inorganic materials, the principles described are also applicable to molecules and atoms in gaseous and liquid states.