A sound suppressor, commonly referred to as a silencer, is a device meant to muffle or suppress the report of a firearm. There are two basic types: the muzzle suppressor and the integral suppressor.
The muzzle suppressor, the most common and most widely-known type of silencer, is screwed on to the end of the barrel in order to drastically increase its overall volume. When the high-pressure gas that is expelling the bullet finally escapes the barrel, its pressure has been diminished by the increase in volume, thus suppressing the report. Most handguns require a new, threaded barrel to be installed, allowing the suppressor or a quick-detach device to be screwed on. However, threading can be added to the existing barrels of certain handguns, such as the Baretta 92.