In woodworking and construction, a nail is a pin-shaped object of metal (or wood, called a treenail or "trunnel") which is used as a fastener, as a peg to hang something, or sometimes as a decoration. Generally nails have a sharp point on one end and a flattened head on the other, but headless nails are available. Nails are made in a great variety of forms for specialized purposes. The most common is a wire nail. Other types of nails include pins, tacks, brads, and spikes.