Here's why:

* Metals are generally strong, malleable (can be shaped), ductile (can be drawn into wires), and good conductors of heat and electricity. These properties are all characteristic of nails.

* Nonmetals are generally brittle, poor conductors, and tend to be gases or solids at room temperature.

* Metalloids have properties that fall somewhere between metals and nonmetals.

While some specialized nails might be made of other materials (like plastic), the vast majority of nails are made from steel, which is an alloy primarily composed of iron, a metal.