This book describes the status of photoelectron spectroscopic techniques, both theoretical and experimental, that have been applied to the study of the cuprate ('high-temperature') superconductors, together with the results derived from such measurements. The techniques described include angle-resolved photoelectron spectroscopy of valence electrons, core level spectra (XPS), and some special variations, such as resonance photoemission. Attention is paid to the difficulties in interpretation of such spectra and to the problems in obtaining good sample surfaces and high resolution. Some comparison with results from other experimental techniques is made. The authors also outline expected future developments in the techniques. This book will be of great interest to graduate students and researchers in physics, chemistry and materials science with an interest in high temperature superconductors.