Self-tapping screws are screws that can tap their own hole as they are driven into the material. They are used to create threads in materials such as wood, plastic, and metal, and are ideal for combining two different types of materials or for screwing in areas where access is only one-sided. Self-tapping screws come in a variety of tip and thread patterns, and are available with almost any possible screw head design. There are two types of self-tapping screws: thread-forming and thread-cutting. Thread-forming screws are meant for plastic, deforming the material as the screw enters, while thread-cutting screws are typically used for wood and metal, literally removing some of the material and creating a threaded path for the screw. Self-tapping screws are generally easy to install and can be used with a variety of tools, including power drills and screwdrivers. One of the main advantages of self-tapping screws is that they do not require pre-tapping, which is the process of creating threads in the material before inserting the screw. Self-tapping screws are used in a variety of applications ranging from DIY carpentry to surgery.