"Progressive rock, sometimes shortened to prog rock or prog, is a form of rock music that evolved in the late 1960s and early 1970s, principally from psychedelic rock, and ultimately as a result of experimentation with electronic keyboard instruments, jazz-rock fusion, blues, and mainly classical music.  Progressive rock compositions are more elaborate than the standard rock or popular verse-chorus based song structures. As well, the arrangements often incorporate elements drawn from classical, jazz, world music, avant-garde music, hard rock, and heavy metal. Songs with lyrics, are often conceptual, philosophical, or based in fantasy. . . read more  "-Wikipedia