A song-plugger was a piano player employed by music stores in the early 20th century to promote and help sell new sheet music, which is how hits were advertised before quality recordings were widely available. Typically, the pianist sat on the mezzanine level

Mezzanine (architecture)

In architecture, a mezzanine or entresol is an intermediate floor between main floors of a building, and therefore typically not counted among the overall floors of a building. Often, a mezzanine is low-ceilinged and projects in the form of a balcony. The term is also used for the lowest balcony in...

 of a store and played whatever music was sent up to him by the clerk of the store selling the sheet music. Patrons could select any title, have it delivered to the song plugger, and get a preview of the tune before buying it.

Musicians and composers who had worked as song pluggers included George Gershwin

George Gershwin

George Gershwin was an American composer and pianist. Gershwin's compositions spanned both popular and classical genres, and his most popular melodies are widely known...

 http://www.gershwinfan.com/biogeorge.html, Ron Roker

Ron Roker

Ron Roker is an English songwriter and singer.-Career:Roker first worked as a song-plugger. His first taste of chart success was provided by the theme music to children's TV programme The Adventures of Rupert Bear. The song "Rupert", co-written with Len Beadle and recorded by Beadle's wife Jackie...

, Jerome Kern

Jerome Kern

Jerome David Kern was an American composer of musical theatre and popular music. One of the most important American theatre composers of the early 20th century, he wrote more than 700 songs, used in over 100 stage works, including such classics as "Ol' Man River", "Can't Help Lovin' Dat Man", "A...

 and Lil Hardin Armstrong

Lil Hardin Armstrong

Lil Hardin Armstrong was a jazz pianist, composer, arranger, singer, and bandleader, and the second wife of Louis Armstrong with whom she collaborated on many recordings in the 1920s....

.

Later, the term was used to describe individuals who would pitch new music to performers, with The New York Times

The New York Times

The New York Times is an American daily newspaper founded and continuously published in New York City since 1851. The New York Times has won 106 Pulitzer Prizes, the most of any news organization...

describing such examples as Freddy Bienstock

Freddy Bienstock

Freddy Bienstock was an American music publisher who built his career in music by being the person responsible for soliciting and selecting songs for Elvis Presley's early albums and films.-Early life:...

 performing a job in which he was "pitching new material to bandleaders and singers".In 1952 Ernest Havemann wrote:

There are about 600 song-pluggers in the U.S.; they have their own union; they are powerful enough to bar all outsiders; and they command fees up to $35,000 a year plus unlimited expense accounts. Their job is to persuade the record companies to use songs put out by their publishing houses and the radio station disk jockeys to play the records."

Song plugging remains an important part of the industry. Record labels and managers will actively search for songs that their artist can record, release and perform, especially those that don't write their own material.

Song plugging is not a science and many companies approach the role differently. Essentially the key objective is to connect songs with record label A&R

A&R

Artists and repertoire is the division of a record label that is responsible for talent scouting and overseeing the artistic development of recording artists. It also acts as a liaison between artists and the record label.- Finding talent :...

.

The process of song plugging is ultimately about creating leads and sourcing good quality songs. The song plugger would typically charge a fee for their services.