A house band is a group of musicians, often centrally organized by a band leader, who regularly play at an establishment. It is widely used to refer both to the bands who work on entertainment programs on television or radio, and to bands which are the regular performers at a nightclub, especially jazz and R&B clubs. The term can also refer to a group that plays sessions for a specific recording studio. House bands on television shows usually play only cover songs instead of originals, and they play during times that commercials would be seen by the home viewing audience. Therefore, only those present in the studio during the show's taping see their full performances. History House bands emerged with jazz music in Chicago during the 1920s. The practice of using regular backing musicians during studio sessions became customary as a means for record companies to save money and add convenience at a time when the music industry had seen increased studio costs and musical specialization. With the advent of television in the 1950s, bands from the swing era of jazz typically performed on variety show programs as house bands, starting a television institution that survives to the present. One of the best-remembered, and longest-running, house bands was the NBC Orchestra of The Tonight Show Starring Johnny Carson and his predecessors. Late-night television offered security and survival for the big band, led by trumpeter Doc Severinsen, while the trends in popular music continually changed around them. Late Night with David Letterman, which began in 1982, featured Paul Shaffer and The World's Most Dangerous Band, who, unlike previous house bands, incorporated contemporary rhythm and blues and rock music. The band continued that blend with Letterman when he left for CBS to start Late Show in 1993. House bands remain a late-night talk show fixture, with many of them also serving as straight men for the host's jokes, musically introducing guests, playing in and out of commercials, composing original pieces of music for sketches, and backing up musical guests. The Roots became the first hip hop house band on late-night television when they joined Late Night with Jimmy Fallon in 2009. Association with record labels and studios Record labels have often employed a core group of musicians to serve as a house band or house orchestra, specifically for recording sessions. These groups can come to be regarded as an important component of