All engineers are concerned with the structural safety, serviceability and the economics of the constructions with which they are involved. The successful approach to the problem can only be established through a sound knowledge of computational methods of engineering and a thorough understanding of the properties and behavior of engineering materials. Without a proper knowledge of materials neither the structural safety and serviceability nor the economics can be achieved in engineering projects. The purpose of this course is to emphasize the basic principles necessary for an understanding of the fundamental nature and properties of engineering materials and to make clear the significance of these principles in engineering practice. The objective has been to present a unified treatment of a variety of materials, stressing the fundamentals which provide a common basis for explaining the behavior of the varied materials. The organization of the course material is such that, first, the elements of the atomic and electronic structure of matter are introduced and the structure types of solids are explained. Then, the physicochemical aspects of the colloidal material used in industrial practice are covered.  A sequence proceeds from atomic structures to coarser structures, from the simple to the more complex. Such a sequence from atoms to crystals, to phases, to microstructures and to macrostructures is followed because the grosser structures and properties depend on the finer structural characteristics. Considering the importance of the mechanical behavior of materials and the limitation of the course period, emphasis is given to the phenomena associated with the mechanical behavior of the materials and their structural characteristics. Elasticity, plasticity and flow phenomena are explained by reference to the main types of engineering materials and a discussion of the strength and other related properties of the materials follows. Finally the effect of radiation damage on the mechanical properties of materials is briefly discussed.