How to use self tapping screws?

Self-tapping screws are divided into self-tapping tips, self-tapping screws, self-tapping teeth, tapping screws, tapping teeth, screwdriver, tapping teeth. Self-tapping tip can be non-porous, that is, do not need to punch, you can directly lock the wood, directly clenched. 

Other tapping need to match the hole can be locked. Which cut the tail and the two teeth are more suitable for plastic clenched, the product will be firmly locked.