Basic course designed to provide a foundation for correlating defect structure and microstructure with physical, mechanical and chemical properties of engineering materials. The fundamental properties of point, line and surface defects in ordered media will be formulated. The thermodynamics of point defects in various types of solids will be discussed as well as the geometry and mechanics of crystal dislocations and their role in crystal plasticity elucidated. The essential elements of microstructure will be characterized emphasizing the concepts of phase constitution, microconstituent, polycrystalline aggregate and multiphase materials. The concept of real materials embodying a hierarchy of structures is emphasized. The principles governing the genesis and stability of material structure at various levels will be discussed.