Self-Tapping is a term that refers to a screw's ability to tap its own threads in materials such as woods, plastics and soft or thin metals. Self-tapping screws are different than self-drilling screws, which use a drill bit shaped tip to self-start in these materials.

The two primary types of self-tapping screws are type A and type AB screws. Although they're similar in most ways, the primary difference between the two involves the spacing of their threads.

Type A Self-Tapping Screws feature wider spaced threads very similar to wood screws. They are interchangeable with wood screws, except that type A self-tapping screws are always fully threaded, while wood screws are generally threaded about two-thirds the length of the body of the screw.

They offer a sharp, gimlet point which can sometimes be used to self-start in soft woods, although pre-drilling a pilot hole is safer, in order to avoid splitting of the wood.

Type AB Self-Tapping Screws feature tighter thread spacing and are often referred to as sheet metal screws. The finer thread allows for a tighter grip in thinner materials such as sheet metal.

Like their type A counterparts, they have a sharp, gimlet point. However, they are not generally designed to self-start in hard materials such as metals without a pilot hole.

To find out more about the differences between self-tapping, self-drilling and sheet metal screws, check out our guide that covers these screw styles.