This book describes the central aspects of diffusion in solids and provides easy access to important information about diffusion in metals, alloys, semiconductors, ion-conducting materials, glasses, and nanomaterials. Coverage includes diffusion-controlled phenomena such as ionic conduction, grain-boundary, and dislocation pipe diffusion. This book will benefit graduate students in disciplines such as solid-state physics, physical metallurgy, materials science, and geophysics, as well as scientists in academic and industrial research laboratories. Diffusion is a vital topic in solid-state physics, chemistry, physical metallurgy, and materials science. Diffusion processes are ubiquitous in solids at elevated temperatures. A thorough understanding of diffusion in materials is crucial for materials development and engineering.