Humankind,materials,and engineering have evolved over the passage of time and are continuing to do so, All of us live in a world of dynamic change,and materials are no exception. The advancement of civilization has historically depended on the improvement of materials to work with. Prehistoric humans were restricted to naturally accessidle materials such as stone, wood, bones, and fur. Over time, they moved from the materials Stone Age into the newer Copper (Bronze) and Iron Ages. Note that this advance did not take place uniformly everywhere- we shall see that this is true in nature even down to the microscopic scale. Even today we are restricted to the materials we can obtain from earth's crust and atmosphere. According to Webster's dictionary, materials may be defined as substances of which something is composed or made. Although this definition is broad, from an engineering application point of view, it covers almost all relevant situations.