Self-Tappers screws are those that tap threads into the material. Self-Tappers screws are used for all sorts of applications including wood, metal, and brick. These screws need a pilot hole to be pre-drilled before installation, as they can drill through the metal by themselves.
By using a drill bit, a pilot hole of slightly smaller diameter than that of the screw is created and during installation, the threads of the screw tap the metal or wood. This tapping action keeps the material fastened together. There are many different types of points that a Self-Tappers screw can have that assist in the tapping of threads into various substrates.