Design is the process of translating a new idea or a market need into thedetailed information from which a product can be manufactured. Each ofits stages require decisions about the materials of which the product is to be made and the process for making it. Normally, the choice of material isdictated by the design. But sometimes it is the other way around: The newproduct, or the evolution of the existing one, was suggested or made possible by a new material. The number of materials available to engineers is vast: 160,000 or more. Although standardization strives to reduce the number, the continuing appearance of new materials with novel and exploitable properties expands the options further. How, then, do engineers choose, from this vast menu, the material best suited to their purpose? Do they rely on their experience? In the past that was how it was done, passing on this precious commodity to apprentices who, much later in their lives, might themselves assume the role of in-house materials guru.