Aluminum is the second most widely used metal in the world. It is readily available, offers a wide range of properties, and can be shaped, coated, and joined using a variety of methods. This chapter discusses some of the key attributes of wrought and cast aluminum alloys and the classifications, designations, and grades of available product forms. It also explains how aluminum alloys are used in aerospace, automotive, rail, and marine applications as well as in building and construction, electrical products, manufacturing equipment, packaging, and consumer durables such as appliances and furniture.