What is a producer? This is opening up a potential can of worms/Pandora's box, but what I will give is an example, only one, of what a producer can be.
I often wonder what the word "producer" means. When people ask me if I produce records I answer with a hesitant "yes." I don't know. I feel like a lot of times I co-produce with a band. I don't feel like I'm running sessions with an iron fist, rewriting songs, dictating tempos and forcing my own vision on the band. Instead I play it pretty mellow, trying to capture what's best about the group, offering sonic ideas and such. I've worked in a few sessions where there was a producer on hand but it wasn't until recently where it became apparent what a producer could be.
The band was well rehearsed and had even demoed many of the songs at home. The producer showed up the day before the session with a bunch of notes culled from the demos and sat in on a practice suggesting ideas. They came in the next day and I concentrated on being an engineer — getting good sounds, watching levels, keeping records, making rough mixes and all. The producer worked on getting guitar tones, watching the tempos, keeping an ear out for tuning problems and, most importantly, looking for the best take of each song. His ideas on how the instruments would fit together and what made a great take made my job easier — I could just focus on getting what was happening onto tape.