This book discusses the study of microstructures of various materials and their classifications. It also focuses on different types of chemical bonds and the arrangement of atoms in materials. It also explains how the defects or imperfections in materials control their properties and explains the different types of strengthening mechanisms used to improve the strength of materials. This book also discusses the characterization methods used to study the mechanical properties, stress-strain curves, basics of polymers, their types, properties, and applications. Basics of powder metallurgy, mechanism of sintering, advantages and dis-advantages of powder metallurgy were explained in detail. Basic principles of corrosion, types, mechanism, and corrosion control methods, fundamentals of composite materials, their types, properties and applications are discussed in this book.