A self-tapping screw is a screw that can tap its own hole as it is driven into the material. Self-tapping screws come with a sharp, piercing tip or a flat, blunt tip. More narrowly, self-tapping is used only to describe a specific type of thread-cutting screw intended to produce a thread in relatively soft material or sheet materials, excluding wood screws. The sharp-tipped screws are designed for drilling their own hole into softer materials such as wood and plastic so they don't need a pilot hole. Other specific types of self-tapping screws include self-drilling screws and thread rolling screws. The advantage of the flat-tipped screw is that it won't get stuck in the material and break off.