A metallic element, compound or alloy is characterized by high structural strength, opacity to light, optical luster, malleability, ductility, and good thermal and electrical conductivity. Most pure metals are combined with one or more metallic or non-metallic components in varied proportions to achieve desired characteristics of structural hardness, resistance to corrosion, suitable color and luster. This combination of metals and other components results in the formation of alloys. The most commonly used alloys of iron are steel, stainless steel, cast iron, etc. are used in a variety of industries like construction, automobile industry, etc. Since the study of metals is fundamental to all areas of engineering. This book aims to expound some key concepts and theories related to the science of metals and alloys in detail and provide extensive information on their practical applications. With state-of-the-art inputs by acclaimed experts working in this field, this book is meant for materials scientists, engineers, experts and students.