A combination of metals or a combination of one or more metals with non-metallic elements which retains the characteristics of a metal is known as an alloy. It is defined by a metallic bonding character. An alloy can be a mixture of metallic phases or a solid solution of metal elements. Alloys with a defined crystal structure and stoichiometry are intermetallic compounds. Alloys are used in a variety of applications. Steel alloys are used in automobiles and construction of buildings, aerospace industry uses titanium alloys and non-sparking tools are produced using beryllium-copper alloys. Sometimes, while preserving important properties, a combination of metals may reduce the overall cost of the material. In other cases, the combination of metals imparts synergistic properties to the constituent metal elements like mechanical strength or corrosion resistance. Steel, brass, solder, bronze, and amalgams are a few examples of alloy. This book contains some path-breaking studies on metallurgy and engineering related to alloys. It outlines the processes and applications of alloys in detail. This book includes contributions of experts and scientists which will provide innovative insights into the topic.