Black Sabbath were an English heavy metal band formed in Birmingham in 1968 by guitarist Tony Iommi, drummer Bill Ward, bassist Geezer Butler and vocalist Ozzy Osbourne. After adopting the Black Sabbath name in 1969, they distinguished themselves through occult themes with horror-inspired lyrics and down-tuned guitars. Their first three albums, Black Sabbath, Paranoid, and Master of Reality (1971), were commercially successful, and are cited as pioneering albums in the development of heavy metal. Subsequent albums Vol. 4 (1972), Sabbath Bloody Sabbath (1973), Sabotage (1975), Technical Ecstasy (1976), and Never Say Die! (1978) saw the band explore more experimental and progressive styles.