Hardness is one the most important properties of solid materials and requires a comprehensive treatment. There are books on hardness testing and on the hardnesses of particular types of materials, but there are none that treat the physics and chemistry of the subject in a general way. Atomic Basis of Mechanical Hardness presents a general introduction for materials scientists and mechanical engineers who are interested in hardness measurement and the connection between hardness and fundamental materials properties. Various materials types are discussed in individual chapters.