[custom_adv] The composer is the person who creates the music for the show. This usually refers to the music in the songs, but it can also include the underscoring for the scenes and even the dance music. The composer's job has changed dramatically over time. [custom_adv] During the early days of American musical theater, the mid to late 19th century, many shows didn't even have a composer of record. Whoever was producing the show would assemble the score from preexisting popular songs, and perhaps hire someone to write a few new songs for the show. Sometimes numerous composers would contribute to a show's score, which often meant a lack of overall cohesion to the music. [custom_adv] Early in the 20th century, shows with just one composer became the standard, although the task of creating the dance music and underscoring (the music that plays under a scene of dialogue) might have fallen to someone else. [custom_adv] As musicals became more integrated and cohesive, composers began to create all of the music in the production to keep it stylistically unified. Even so, many shows in the first half of the century included songs from a composer's "trunk" of already-written or already-popular songs rather than songs written expressly to tell a particular story; Irving Berlin and Cole Porter musicals (and musical movies) frequently did this, for instance. [custom_adv] The composer is likely to work with an orchestrator, who arranges the music for all the different instruments (many composers initially write their scores at the piano, emphasizing vocal lines and accompaniment).
