answer:Two of several methods for working steel. Google up some stuff on metallurgy, steelsmithing, and the like. Wikipedia is a good place to start, but they don’t really go into depth. Folding is to steel what kneading is to dough: you fold it over, hammer it flat, fold it over, hammer it flat, etc. for the sake of improving its strength. Layered steel (or else pattern welding, the more advanced form) is where you get several sheets of steel, heat them up, and then hammer them together. A skilled craftsman can produce a visually appealing pattern. Both sorts exploit properties of steel that cannot be had via methods like drop-forging or die-casting.