A nail gun is a tool used to drive nails into wood, drywall, rolled steelwork, and other hard materials. Nail guns are available in a number of different styles and sizes, including special models for framing, roofing and sidings. Because they can replace a hammer in most cases, saving the user time and effort, nail guns have become standard among both professional and amateur builders. A nail gun can be powered by compressed air, electricity or batteries, or electromagnetism. Some small guns are powered by butane, a fuel that causes a small explosive charge to drive the nail into the wood.

The most common type of nail gun is the pneumatic nailer, which works with compressed air. When the trigger is pulled, air pressure builds up, driving the nail out. Although cost-effective, easy to use, and highly powerful, a pneumatic nail gun has the disadvantage of depending on a bulky air compressor to work. For on-site jobs, however, this type of nail gun is the preferred choice.

As there is less risk of splitting the wood grain when using a nail gun than when using a hammer, nail guns are especially useful in delicate projects such as the application of indoor trimming. A nail gun sets the nail in one motion, reducing the chance of slips and bumps that can ruin delicate woods. Most models also include a rubber safety nose to protect the wood from friction.

Nail guns have long been considered a safety hazard. They are powerful and achieve high velocity, and can be dangerous if mishandled. In fact, over a thousand serious accidents are reported every year from nail gun mishandling. Caution is a must when working with one.

Professional-grade varieties are automatic, and fire a nail directly upon pulling the trigger. A semi-automatic nail gun is more appropriate for beginners, since it requires a two step process: pull the trigger and then tap the barrel against the wood. This safety feature protects the user from accidentally firing a nail gun and injuring himself or others. Some states now require a special permit or registration to allow the acquisition of a nail gun.

A good-quality starter set, including both a compressor and a small nail gun, can be bought for around 200 US dollars (USD). More sophisticated models can reach 1000 USD or more. Optional features such as a hard-shell case, safety trigger, and depth adjustment can drive the price even higher. For one-time jobs, a nail gun can also be rented at hardware stores and home repair centers.