The materials used in all branches of construction are commonly called engineering materials or materials of construction. The most important of these, as iron, steel, brass, wood, stone, etc., are well known. There are many other materials less extensively used, and more or less widely known.

Another class of materials necessary to the various processes include those employed to assist the processes, though not intended to enter into the finished product, as fuel, flux in smelting and in welding, emery in grinding, sand in moulding, etc.