The properties of materials are altered, sometimes radically, when very high pressures are applied. This book surveys the apparatus available for high pressure studies with a particular emphasis on diamond anvil cells and related equipment. It also examines pressure measurement techniques at extreme values. A large part of the book considers the experimental needs and arrangement for studies involving the interaction of high pressures with high and low temperatures, magnetic fields, and shock waves. Optical properties, Brillouin and Raman scattering, infrared spectroscopy, eletron spin and nuclear magnetic resonance at high pressures are also covered.