Led Zeppelin IV is the common, but unofficial name of the untitled fourth album of English rock band Led Zeppelin. It was released on November 8, 1971. It has no official title printed anywhere on the album, but is generally called Led Zeppelin IV after the band's previous three numbered albums. Atlantic Records catalogs have used the names Four Symbols (see below) and The Fourth Album; it has also been referred to as Zoso, which the first symbol appears to spell. Led Zeppelin guitarist Jimmy Page frequently refers to the album in interviews as "the fourth album" and Led Zeppelin IV, while singer Robert Plant thinks of it as "the fourth album, that's it". After the band's reunion at the Ahmet Ertegun tribute, they made it known that the unknown name is simply "The Fourth Album." Led Zeppelin IV was a huge success commercially and critically when it was released. Most of album's songs are staples on classic rock radio stations, including "Black Dog", "Rock and Roll", "When the Levee Breaks", and "Stairway to Heaven". The album is one of the best-selling albums in history, with over 23 million units sold in the United States, third most for any album all-time.In 2003, the album was ranked number 66 on Rolling Stone magazine's list of the 500 greatest albums of all time. Jimmy Page acoustic guitar, electric guitar, mandolin, producer Robert Plant vocals, harmonica John Paul Jones synthesizer, bass guitar, keyboards, mandolin, recorders John Bonham drums Ian Stewart piano (on Rock and Roll", uncredited) Sandy Denny vocals (on track 3) Peter Grant executive producer George Chkiantz mixing Andy Johns engineer, mixing Graphreaks design coordinator Barrington Colby Mom inside illustration (The Hermit) CD Mastering engineers Joe Sidore - original CD (mid-1980s) George Marino - remastered CD (1990) Released November 8, 1971 Recorded December 1970 March 1971 at Headley Grange, Hampshire, with The Rolling Stones Mobile Studio; Island Studios, London; Sunset Sound, Los Angeles. Mixed at Island Studios, London; Olympic Studios, London. Genre Hard rock, heavy metal, blues-rock, folk rock Length 42:39, Label Atlantic Producer Jimmy Page