A 'tang' is the protrusion of the steel into the handle of a knife or tool. The tang extension into the handle not only provides a way of attaching the handle, but improves the weight and balance of the knife, and adds strength and durability. This how to video is small overview of how you can make hidden tang knife. The blade was ground to shape and heat treated before. Th blade material used in this tutorial is CPM-S30V, a special knifesteel.