An impact wrench is a power tool that is designed to deliver high torque output with minimal exertion by the user, by storing energy in a rotating mass, then delivering it suddenly to the output shaft. It is also known as an impactor, impact gun, air wrench, air gun, rattle gun, torque gun, or windy gun. Impact wrenches are widely used in many industries, such as automotive repair, heavy equipment maintenance, product assembly, major construction projects, and any other instance where a high torque output is needed.

An impact wrench typically uses a square drive that you attach a socket to, and it can deliver more torque and accept larger tool bits than an impact driver. This makes the impact wrench more suitable for large bolts and nuts in heavy mechanical settings, like lug nuts, while the impact driver with its lesser torque and smaller tool bit is more suited towards driving smaller screws, like in construction work.

Impact wrenches can be powered by compressed air, electricity, hydraulic power, or batteries. They work by applying short bursts of a twisting motion that is effective at loosening or tightening bolts. The high torque output is produced through a hammering action at a low speed, rather than constant rotations at high speed like that of an air drill.

In summary, an impact wrench is a powerful tool that is used to effortlessly deliver high torque output used to loosen or tighten bolts, lug nuts, and fasteners in a wide range of environments from DIY enthusiasts to professionals in various industries.