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 cleats.
Nails are typically driven into the workpiece by a hammer, a pneumatic nail gun, or a small explosive charge or primer. A nail holds materials together by friction in the axial direction and shear strength laterally. The point of the nail is also sometimes bent over or clinched after driving to prevent pulling out.
is a rotary control used to provide input to a device when grasped by an operator and turned, so that the degree of rotation corresponds to the desired input. Such knobs are one of the most common components in control systems and are found on all sorts of devices.