A nail gun or nailgun or nailer is a type of tool used to drive nails into wood or some other kind of material. It is usually driven by electromagnetism, compressed air, or, for powder-actuated tools, a small explosive charge. Smaller nail guns are often called brad Nailers, bradders, or pin nailers. Nail guns have in many ways replaced Hammers as tools of choice amongst builders.

Why use a nail gun?

Nail guns also have many advantages over hammers, as they drive the fastener instantly, without splitting the wood, and consistently set the nail head below the surface. Most nailguns can be set to operate in either of two modes:

• In one mode, the nail gun must first be pressed against the workpiece and the trigger then depressed. One nail is then fired and the trigger must be released before the next nailing cycle can commence.
• In the other mode, the triggger is depressed before the nail gun is brought into contact with the workpiece. Then, each time the nail gun is pressed against the workpiece, a nailing cycle commences and one nail is fired. By repeatedly "bumping" the nail gun against the workpiece, any number of nails can be rapidly fired. This mode is very fast, although less precise than the first mode.

Nail guns do not use conventional nails. Instead, the nails are provided mounted in long strips (similar to a stick of staples) or in a plastic carrier coil. Each style of nail gun will be either stick- or coil-loading, although it may operate with nails of a variety of lengths. The gauge (thickness) of the nail is usually fixed for any given model of nail gun.

Safety

All kinds of nail guns can be dangerous, so safety precautions similar to those for a firearm are usually recommended for their use. For safety, nail guns are designed to be used with the muzzle touching the target; they are short-range and inaccurate if a user tries to use one as a projectile weapon. Explosive-powered ("powder actuated") nailguns fall into two broad categories:

Direct drive or high velocity devices. This uses gas pressure acting directly on the nail to drive it.
Indirect drive or low velocity devices. This uses gas pressure acting on a heavy piston which drives the nail. Indirect drive nailers are safer because they cannot launch a free-flying projectile even if tampered with or misused, and the lower velocity of the nails are less likely to cause explosive shattering of the work substrate.
Either type can, with the right cartridge loads, be very powerful indeed, driving a nail or other fastener into hard concrete, stone, or rolled steelwork with ease. Perhaps the most famous manufacturer of indirect-drive fastening tools is Hilti of Liechtenstein.

Some areas of the world may need registration, secure storage or other measures to regulate the possession and use of nailguns.