Nobody seems to be exactly sure what a producer does or what their job description actually entails. Yet we know a producer when we see one: George Martin for the Beatles, Teo Macero for Miles Davis, Brian Wilson for the Beach Boys, Phil Spector for Tina Turner or Quincy Jones for Michael Jackson. At the very least, we assume they do something that makes them worthy of mentioning in the same breath as the artist, but few people actually know what that ‘something’ is. In this chapter we will explore how the producer's role has changed from the early days of sound recording to our day, and what we can learn from that. As audio technology (the technology of accurately handling the audio signal) becomes music technology (the creative application of audio technology to musical ends), the producer becomes arranger and composer, and eventually performing musician.