Self-tapping screws cut precise threads when they are screwed into wood, plastic or metal. It's helpful to use self-tapping screws for products that you need to maintain regularly such as air-conditioning units or canopies where you need to dissemble and reassemble the item along the same threads. You can insert self-tapping screws with either a hand-held or electric screwdriver.
Before you use self-tapping screws, it's helpful, although not mandatory, to drill a pilot hole through the material. This ensures the screw will go in easily and will be positioned correctly. Make sure to use a smaller drill bit than the self-tapping screw itself when drilling the pilot hole. Otherwise, if the hole is too large, the screw threads won't have anything to attach to.