Released in 1971 Zeppelin IV remains the bands most admired work, and is a masterpiece of 1970s hard rock. Following the lukewarm critical reviews of their third album, Jimmy Page decided to release IV as an untitled album with each band member represented by a hand drawn symbol on the record's label and sleeve instead of a title. Although the record label insisted on having a title, Page held his ground, as he thought it would be an answer to critics who he felt could not review a Zeppelin album without referencing another earlier one. Considered their defining album, Zeppelin IV features many beloved songs including "Black Dog", "Rock and Roll", and of course "Stairway to Heaven", and is one of the best-selling albums of all time, having sold over 37 million copies.