This book is the first of a three-volume series written by the same author. It aims to deliver a comprehensive and self-contained account of the fundamentals of the physics of solids. In the presentation of the properties and experimentally observed phenomena together with the basic concepts and theoretical methods, it goes far beyond most classic texts. The essential features of various experimental techniques are also explained. The text provides material for upper-level undergraduate and graduate courses. It will also be a valuable reference for researchers in the field of condensed matter physics.