Black Sabbath have been so influential in the development of heavy metal rock music as to be a defining force in the style. The group took the blues-rock sound of late-'60s acts like Cream, Blue Cheer, and Vanilla Fudge to its logical conclusion, slowing the tempo, accentuating the bass, and emphasizing screaming guitar solos and howled vocals full of lyrics expressing mental anguish and macabre fantasies. If their predecessors clearly came out of an electrified blues tradition, Black Sabbath took that tradition in a new direction, and in so doing helped give birth to a musical style that continued to attract millions of fans decades later.

The group was formed by four teenage friends from Aston, near Birmingham, England: Anthony "Tony" Iommi (b. Feb 19, 1948), guitar; William "Bill" Ward (b. May 5, 1948), drums; John "Ozzy" Osbourne (b. December 3, 1948), vocals; and Terence "Geezer" Butler (b. July 17, 1949), bass. They originally called their jazz-blues band Polka Tulk, later renaming themselves Earth, and they played extensively in Europe. In early 1969, they decided to change their name again when they found that they were being mistaken for another group called Earth. Butler had written a song that took its title from a film directed by Mario Bava, Black Sabbath, and the group adopted it as their name as well. As they attracted attention for their live performances, record labels showed interest, and they were signed to Philips Records in 1969. In January 1970, the Philips subsidiary Fontana released their debut single, "Evil Woman (Don't Play Your Games with Me)," a cover of a song that had just become a U.S. hit for Crow; it did not chart. The following month, a different Philips subsidiary, Vertigo, released Black Sabbath's self-titled debut album, which reached the U.K. Top Ten. Though it was a less immediate success in the U.S. -- where the band's recordings were licensed to Warner Bros. Records and appeared in May 1970 -- the LP broke into the American charts in August, reaching the Top 40, remaining in the charts over a year, and selling a million copies.

Appearing at the start of the '70s, Black Sabbath embodied the Balkanization of popular music that followed the relatively homogenous second half of the 1960s. As exemplified by its most popular act, the Beatles, the '60s suggested that many different aspects of popular music could be integrated into an eclectic style with a broad appeal.the Beatles were as likely to perform an acoustic ballad as a hard rocker or R&B-influenced tune. At the start of the '70s, however, those styles began to become more discrete for new artists, with soft rockers like James Taylor andthe Carpenters emerging to play only ballad material, and hard rockers like Led Zeppelin and Grand Funk Railroadtaking a radically different course, while R&B music turned increasingly militant. The first wave of rock critics, which had come into existence with the Beatles, was dismayed with this development, and the new acts tended to be poorly reviewed despite their popularity. Black Sabbath, which took an even more extreme tack than the still blues- and folk-based Led Zeppelin, was lambasted by critics (and though they eventually made their peace with Zeppelin, they never did with Sabbath). But the band had discovered a new audience eager for its uncompromising approach.

Black Sabbath quickly followed their debut album with a second album,Paranoid, in September 1970. The title track, released as a single in advance of the LP, hit the Top Five in the U.K., and the album went to number one there. In the U.S., where the first album had just begun to sell, Paranoid was held up for release until January 1971, again preceded by the title track, which made the singles charts in November; the album broke into the Top Ten in March 1971 and remained in the charts over a year, eventually selling over four million copies, by far the band's best-selling effort. (Its sales were stimulated by the belated release of one of its tracks, "Iron Man," as a U.S. single in early 1972; the 45 got almost halfway up the charts, the band's best showing for an American single.)

Master of Reality, the third album, followed in August 1971, reaching the Top Ten on both sides of the Atlantic and selling over a million copies. Black Sabbath, Vol. 4 (September 1972) was another Top Ten million-seller. ForSabbath Bloody Sabbath (November 1973), the band brought in Yeskeyboard player Rick Wakeman on one track, signaling a slight change in musical direction; it was Black Sabbath's fifth straight Top Ten hit and million-seller. In 1974, the group went through managerial disputes that idled them for an extended period. When they returned to action in July 1975 with their sixth album, Sabotage, they were welcomed back at home, but in the U.S. the musical climate had changed, making things more difficult for an album-oriented band with a heavy style, and though the LP reached the Top 20, it did not match previous sales levels. Black Sabbath's record labels quickly responded with a million-selling double-LP compilation, We Sold Our Soul for Rock 'n' Roll (December 1975), and the band contemplated a more pronounced change of musical style. This brought about disagreement, with guitarist Iommi wanting to add elements to the sound, including horns, and singer Osbourne resisting any variation in the formula. Technical Ecstasy (October 1976), which adopted some of Iommi's innovations, was another good -- but not great -- seller, and Osbourne's frustration eventually led to his quitting the band in November 1977. He was replaced for some live dates by formerSavoy Brown singer Dave Walker, then returned in January 1978. Black Sabbath recorded their eighth album, Never Say Die! (September 1978), the title track becoming a U.K. Top 40 hit before the LP's release and "Hard Road" making the Top 40 afterwards. But the singles did not improve the album's commercial success, which was again modest, and Osbourne left Black Sabbath for a solo career, replaced in June 1979 by former Rainbow singer Ronnie James Dio (b. July 10, 1949, d. May 16, 2010). (Also during this period, keyboardist Geoff Nichols became a regular part of the band's performing and recording efforts, though he was not officially considered a bandmember until later.)

The new lineup took its time getting into the recording studio, not releasing its first effort until April 1980 with Heaven and Hell. The result was a commercial resurgence. In the U.S., the album was a million-seller; in Britain, it was a Top Ten hit that threw off two chart singles, "Neon Knights" and "Die Young." (At the same time, the band's former British record label issued a five-year old concert album, Black Sabbath Live at Last, that was quickly withdrawn, though not before making the U.K. Top Five, and reissued "Paranoid" as a single, getting it into the Top 20.) Meanwhile, drummer Bill Ward left Black Sabbath due to ill health and was replaced by Vinny Appice. The lineup of Iommi, Butler, Dio, and Appice then recorded Mob Rules(November 1981), which was almost as successful as its predecessor: In the U.S., it went gold, and in the U.K. it reached the Top 20 and spawned two chart singles, the title track and "Turn Up the Night." Next on the schedule was a concert album, but Iommi and Dio clashed over the mixing of it, and by the timeLive Evil appeared in January 1983, Dio had left Black Sabbath, taking Appice with him.

The group reorganized by persuading original drummer Bill Ward to return and, in a move that surprised heavy metal fans, recruiting Ian Gillan (b. August 19, 1945), former lead singer of Black Sabbath rivals Deep Purple. This lineup -- Iommi, Butler, Ward, and Gillan -- recorded Born Again, released in September 1983. Black Sabbath hit the road prior to the album's release, with drummer Bev Bevan (b. November 25, 1946) substituting forWard, who would return to the band in the spring of 1984. The album was a Top Five hit in the U.K. but only made the Top 40 in the U.S. Gillan remained with Black Sabbath until March 1984, when he joined a Deep Purple reunion and was replaced by singer Dave Donato, who was in the band until October without being featured on any of its recordings.

Black Sabbath reunited with Ozzy Osbourne for its set at the Live Aid concert on July 13, 1985, but soon after the performance, bassist Geezer Butler left the band, and with that the group became guitarist Tony Iommi's vehicle, a fact emphasized by the next album, Seventh Star, released in January 1986 and credited to "Black Sabbath featuring Tony Iommi." On this release, the lineup was Iommi (guitar); another former Deep Purple singer, Glenn Hughes(b. August 21, 1952) (vocals); Dave Spitz (bass); Geoff Nichols (keyboards); and Eric Singer (drums). The album was a modest commercial success, but the new band began to fragment immediately, with Hughes replaced by singer Ray Gillen for the promotional tour in March 1986.

With Black Sabbath now consisting of Iommi and his employees, personnel changes were rapid. The Eternal Idol (November 1987), which failed to crack the U.K. Top 50 or the U.S. Top 100, featured a returning Bev Bevan, bassist Bob Daisley, and singer Tony Martin. Bevan and Daisley didn't stay long, and there were several replacements in the bass and drum positions over the next couple of years.Headless Cross (April 1989), the band's first album for I.R.S. Records, found veteran drummer Cozy Powell (b. December 29, 1947, d. April 5, 1998) and bassist Laurence Cottle joining Iommi and Martin. It marked a slight uptick in Black Sabbath's fortunes at home, with the title song managing a week in the singles charts. Shortly after its release, Cottle was replaced by bassistNeil Murray. With Geoff Nichols back on keyboards, this lineup made TYR (August 1990), which charted in the Top 40 in the U.K. but became Black Sabbath's first regular album to miss the U.S. charts.

Iommi was able to reunite the 1979-1983 lineup of the band -- himself,Geezer Butler, Ronnie James Dio, and Vinny Appice -- for Dehumanizer(June 1992), which brought Black Sabbath back into the American Top 50 for the first time in nine years, while in the U.K. the album spawned "TV Crimes," their first Top 40 hit in a decade. And on November 15, 1992, Iommi, Butler, and Appice backed Ozzy Osbourne as part of what was billed as the singer's final live appearance. Shortly after, it was announced that Osbourne would be rejoining Black Sabbath.

That didn't happen -- yet. Instead,Dio and Appice left again, andIommi replaced them by bringing back Tony Martin and adding drummer Bob Rondinelli. Cross Purposes(February 1994) was a modest seller, and, with Iommi apparently maintaining a Rolodex of all former members from which to pick and choose, the next album, Forbidden (June 1995), featured returning musicians Cozy Powell, Geoff Nichols, and Neil Murray, along with Iommi and Martin. The disc spent only one week in the British charts, suggesting that Black Sabbath finally had exhausted their commercial appeal, at least as a record seller. With that, the group followed the lead of the Eagles and Fleetwood Mac, putting the most popular lineup of the band back together for a live album with a couple of new studio tracks on it. Recorded in the band's hometown of Birmingham, England, in December 1997, the two-CD set Reunion -- featuring all four of Black Sabbath's original members, Iommi, Osbourne, Butler, and Ward -- was released in October 1998. It charted only briefly in the U.K., but in the U.S. it just missed reaching the Top Ten and went platinum. The track "Iron Man" won Black Sabbath their first Grammy Award for Best Metal Performance. The band toured through the end of 1999, concluding their reunion tour on December 22, 1999, back in Birmingham.

In February 2001, Black Sabbath announced that they would reunite once again to headline the sixth edition of Ozzfest, Osbourne's summer concert festival, playing 29 cities in the U.S. beginning in June. More surprisingly, the group also announced their intention to record a studio album of all-new material, the original lineup's first since 1978. By the end of the year, a failed recording session with producer Rick Rubin proved what an unreasonable idea this was, and the band laid dormant while Osbourne enjoyed scoring a hit TV series the following spring. The band split once more. Osbourne went on recording and touring on his own, while Iommi and Butler reunited withVinny Appice and Ronnie James Dio to form Heaven & Hell. The band recorded a live album at Radio City Music Hall, performing Sabbath material from the Heaven and Hell and Mob Rules albums in 2007, before releasing a studio effort entitled Devil You Know in 2009. Dio was diagnosed with cancer and passed away in 2010 of that year.

In late 2011, all four of Black Sabbath's original members announced yet another reunion; this time they claimed the band would record new material as well as tour. Iommi was diagnosed with early-stage lymphoma early in 2012, however, and it was spring before Osbourne, Iommi, and Butler took to the stage on May 19th at O2 Academy in Birmingham, England for their first show together since 2005. At the end of the summer it was announced that the band was indeed working on material for a new album. The long-awaited13 surfaced in the early summer of 2013; however, drummer Bill Ward was absent from the recording process completely. In his stead was Rage Against the Machine drummer Brad Wilk, who provided drums for the album as well as its accompanying live dates. Some evidence of the ensuing tour was documented with the live album Gathered in Their Masses, which arrived before the end of the year.

The band's first single from 13, "God Is Dead?", was released on 19 April 2013. On 20 April 2013, Black Sabbath commenced their first Australia/New Zealand tour in 40 years, to be followed by a major North American Tour in Summer 2013. The second single of the album, "End of the Beginning", debuted on 15 May in a CSI: Crime Scene Investigation episode, where all three members appeared. In June 2013, 13 topped both the UK Albums Chart and the US Billboard 200. "God Is Dead?" earned Black Sabbath their first Grammy Award in 14 years for Best Metal Performance in 2014.

In July 2013, Black Sabbath embarked on a North American Tour (for the first time since July 2001), followed by a Latin American tour in October 2013. In November 2013, the band started their European tour due to last until December 2013. In March and April 2014, they will be making 12 stops in North America (mostly in Canada) as the second leg of their North American Tour before to embark in June 2014 on the second leg of their European tour.