At first, I thought it was just Genesis, ELP, and Yes, but as I've listened to so much music, the prog designation has gotten blured in my mind. I think it's anything that attempts something very complex in rock music, like bringing in influences from classical or jazz. There's also the literary thing. I like music that tells a story and that's often a big part of prog rock. There's something bucolic in it too. I get a very outdoorsy feeling from much of it, maybe because it tends to be gentler than a lot of rock and sometimes has sounds that mimic nature.



