The pioneering Heavy Metal band Black Sabbath was formed in the industrial city of Birmingham, England, in 1968, by four teenage friends: bassist Geezer Butler, guitarist Tony Iommi, singer Ozzy Osbourne, and drummer Bill Ward. At first the quartet, called Earth at the time, played straightforward Blues Rock in the vein of popular bands like Cream. But the band quickly found their own sound: their lyrics took on darker themes, often focusing on occultism and drugs, and the music became thicker, louder and more riff-based. It also became more dissonant, making use of the tritone, or so-called “devil’s chord,” a discordant combination of notes producing an unsettling feeling in the listener. They changed their name to Black Sabbath and became one the earliest rock bands whose music was described as “Heavy Metal.”
Their intense live shows got the attention of record labels, and their first album, “Black Sabbath” (recorded in a single day), and second album, “Paranoid,” were both released in 1970. The two albums proved hugely influential, with many bands soon emulating their dark, dense sound.
Black Sabbath toured incessantly and released six more albums before Osbourne's drug use led to his departure in 1978. His replacement was former Rainbow vocalist Ronnie James Dio, who quit Sabbath in 1982 after three albums. For the next 30 years the band would continue to record and tour with an ever-changing lineup, with original guitarist Tony Iommi the only consistent member, and occasional reunions with Dio and Osbourne, who’d gone on to a successful solo career. In 2013 the original line up (with Brad Wilk from Rage Against the Machine on drums) released a new album, “13.”