Peter Conners - JAMerica : The History of the Jam Band and Festival Scene (2013) [epub]

The term “jam band” is used to categorize a type of music that favors improvisation and musicianship over concise riffs, hooks, and traditional songwriting structure. The term also helps define the fiercely dedicated fans of the music as accurately as it does the bands. Much as with the Grateful Dead—the progenitors of the jam band scene—the survival of the scene depends upon a symbiotic relationship with fans. Jam bands nurture a close relationship with their fans, fostered through constant touring and the mutual belief that each performance is a unique, shared event.