A laugh track is a separate soundtrack for a recorded comedy show containing the sound of audience laughter. In some productions, the laughter is a live audience response instead; in the United States, where it is most commonly used, the term usually implies artificial laughter (canned laughter or fake laughter) made to be inserted into the show. This was invented by American sound engineer Charles "Charley" Douglass.
The Douglass laugh track became a standard in mainstream television in the U.S., dominating most prime-time sitcoms from the late 1950s to the late 1970s. Usage of the Douglass laughter decreased by the 1980s when stereophonic laughter was provided by rival sound companies as well as the overall practice of single-camera sitcoms eliminating audiences altogether.