Metals are a class of materials valued for their strength, durability, and thermal and electrical conductivity. They play a central role in engineering and manufacturing, forming the backbone of everything from machinery and tools to infrastructure and consumer products. Understanding the properties of metals—such as hardness, ductility, corrosion resistance, and machinability—is essential for making informed design decisions and selecting appropriate manufacturing processes. The choice of metal can influence not only performance and cost but also how a part is fabricated, assembled, and maintained. In this way, a solid foundation in the behavior and classification of metals is critical for producing reliable, efficient, and functional designs.