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. This would end up being their last album produced by Bain, as production duties would be taken over by guitarist Tony Iommi for their subsequent albums.