So what is a blues jam and how does it work? Basically, a blues jam a gathering of musicians in a public venue who share a love of the blues that may not have the opportunity to play in a band setting.
Usually there's a signup sheet. Then, throughout the night, the jam master will bring up musicians to play. For instance, he may bring up a guitar player and a singer. Or he may just bring up a drummer. It depends on a number of factors. But in general, he's trying to get everyone a chance to play while trying to put the best groups together to keep it entertaining for the crowd.