This book provides a mechanical properties of materials used in modern Engineering applications. The basic science of each property is provide the knowledge with which to design materials with better properties. Hardness is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. The irregularities at the grain level of the microstructure are responsible for the hardness of a material. In this book the different materials ceramic, polymer and composites properties and its wide applications have been discussed. The smart and nano materials properties and applications have also been discussed.