A sound suppressor or "silencer" is a device either attached to the end of a gun barrel or integrated into the firearm which decreases the report of a gunshot. Early suppressors were intended for sporting use in hunting or target shooting near densely populated areas for "politeness". But suppressors soon found other uses in covert warfare and crime because it's stealthy attributes. The suppressor didn't really come into major use until World War II, most use by the Office of Strategic Services (the predecessor of the Central Intelligence Agency) and even more so during the Cold War (a war fought primarily with information and espionage). Another use for silencers is in buildings where the concussion from gunfire can be deafening.