Psychedelic rock songs sometimes have lyrics describing the effects of drugs, if any words at all. Songs were sometimes very long (10-15 minutes), and much of this time might be taken up by a solo, like a drum solo or a guitar solo. Some major groups that made psychedelic rock included: The Beatles, The Doors, The Byrds, The Grateful Dead, The Who, Jimi Hendrix, Jefferson Airplane, Pink Floyd, Frank Zappa and The Animals.