This module is designed to introduce students to a systematic approach from a scientific viewpoint of the structure, properties and behavior of most conventional and new engineering materials. The sequence proceeds from atomic structure to the coarser structures, namely, phase to microstructure and finally to macrostructure are logical both scientifically and pedagogically, since the grosser structures and properties depend upon the microstructure characteristics. It includes the study of the behavior of materials in service, the modification of these behaviors through different appropriate alloying and heat treatments and composite materials as well.