A nail consists of a metal rod or shank, pointed at one end and usually
having a formed head at the other, that can be hammered into pieces of
wood or other materials to fasten them together. A nail is usually made of
steel, although it can be made of aluminum, brass, or many other metals.
The surface can be coated or plated to improve its corrosion resistance,
gripping strength, or decorative appearance. The head, shank, and point
may have several shapes based on the intended function of the nail. Of the
nearly 300 types of nails made in the United States today, most are used
in residential housing construction. The average wood frame house uses
between 20,000 and 30,000 nails of various types and sizes.
Nails are divided into three broad categories based on their length. In
general nails under 1 inch (2.5 cm) in length are called