Your all-time favorite TRACK

[Yesspaz]

If we were to define "progressive" rock, I'd say that you'd first have to look at the beginning of rock itself. Rock started as a melding of blues, gospel, soul, and country. Think Elvis Presley, Buddy Holly, Little Richard, and Chuck Berry. As Muddy Waters said, "The Blues had a baby, and they named the baby Rock and Roll." So we had all these blues and soul and country based acts. To me, "progressive" rock is rock that breaks away from the original roots. Therefore, classical and jazz were the initial inspirations, and to a lesser extent, world music (think George Harrison). I think today that "progressive rock" generally means rock that follows in the footsteps of the original prog-rockers:

rock music that challenges form and structure, time and instrumentation, complexity and theme.

Yesspaz now broke because that was his last two cents.