This graduate-level text employs a formal, classical viewpoint to survey the fundamentals of quantum optics. Its coverage includes the quantum theory of partial coherence and the nature of the relations between classical and quantum theories of coherence. Students and professional physicists interested in intensity interferometry, photon counting correlations, and lasers will find this volume extremely helpful. Topics include partially coherent light, photoelectric counting distributions, dynamical determination of statistical description, and equations of motion and coherent-state representation of the electromagnetic field. Additional subjects encompass quantum theory of optical correlation phenomena, special state of radiation fields, and intensity interferometry in quantum optics. The text offers particularly complete treatments of properties of the coherent states and of the "diagonal" representations for statistical states. These methods are applied to studies of coherence, coincident counting rates, and counting distributions for a number of physically significant states, including thermal and laser-like fields.