The book "Internal Friction in Metallic Materials" offers a comprehensive collection of experimental data on internal friction, anelastic relaxation, and damping properties of metallic materials. It addresses nearly all phenomena of anelastic relaxation ever published and most effects of internal friction based on other forms of mechanical (elastic) energy dissipation. Additionally, it explains fundamental physical mechanisms of internal friction, summarizes typical effects for various groups of metals, and provides over 2000 references to original works. This specialized book is a valuable resource for researchers and professionals dealing with the mechanical properties of metals and their applications.