Master of Reality is the third studio album by the English heavy metal band Black Sabbath, released on 6 August 1971 by Vertigo Records. It is regarded by some critics as the foundation of stoner rock and sludge metal. Produced by Rodger Bain, who also produced the band's prior two albums, Master of Reality was recorded at Island Studios in London from February to April 1971. Guitarist Tony Iommi and bassist Geezer Butler downtuned their instruments during the production, achieving what Iommi called a "bigger, heavier sound".
Ozzy Osbourne – lead vocals Tony Iommi – guitar, synthesiser on "After Forever" and "Children of the Grave", flute and piano on "Solitude", acoustic guitar on "Orchid", cough on "Sweet Leaf" Geezer Butler – bass Bill Ward – drums, percussion on "Children of the Grave", sleigh bells on "Solitude" Keef – photography, poster design Mike Stanford – art direction
