Black Sabbath started in Birmingham, England in the late 60s under the name Earth. Initially a blues band, Black Sabbath became one of the definitive classic heavy metal bands, to be ranked alongside Led Zeppelin, Deep Purple and Judas Priest.
The band was one of a number of groups reviving the heavy guitar driven sounds of early Cliff Richard and the Shadows recordings. As with all other guitarists of this field i.e. Ritchie Blackmore, Eric Clapton, Jimmy Page, Tony Iommi was greatly influenced by Hank Marvin's (Shadows) playing, which is seen not only in live Black Sabbath shows but also on the album "Twang!: A Tribute to Hank Marvin & the Shadows", an album with Ritchie Blackmore and many other guitar heroes, on which Iommi plays Wonderful Land.
With an extremely gifted rhythm section and the extraordinary on-stage antics of Osbourne the band enjoyed success with their British metal of brutal riffs beginning with their first album, the eponymous Black Sabbath (1970). Its followup, Paranoid (also 1970) brought them a success in America and the UK. The content of the songs (both originals and cover versions) from both albums marked the band as influenced by the occult and black magic. Butler wrote much of the lyrics. Black Sabbath have been cited by some as the source of much doom metal and black metal.
They released a further three albums, Master of Reality (1971), Vol. 4 (1972) and Sabbath Bloody Sabbath (1973) before management problems and the a label change from Vertigo to WWA disrupted the band's release schedule. The next album, Sabotage, was not released until 1975 and its follow-up, Technical Ecstasy (1976) would be the last Ozzy-Era album in the heavy Sabbath style.
In 1978 the band released Never Say Die! and rumours that Osbourne was to leave the band were proved true in 1979 (Osbourne formed Blizzard of Ozz, swiftly renamed to Ozzy Osbourne Band). He was replaced by Ronnie James Dio but Osbourne's departure was clearly the end of an era for the band.
Black Sabbath's first album with Dio, Heaven and Hell, did much to bring back the Sabbath spirit of heavy metal. However, after the departure of original member Ward, with the Mob Rules album, they started to lose their touch, effectively fading into generic heavy metal oblivion. A moderately-successful reunion of all the original Sabbath members was mounted in 1998.
The band rarely received any critical praise ("blundering bozos" was one description) and Osbourne's vocal talent can be safely labelled as exuberant but highly limited. Their musical talent and ingenuity are however irrefutable. They were acknowledged pioneers in the heavy metal field, and many heavy metal bands cite Sabbath as an inspiration, including such famous and successful groups as Iron Maiden and Metallica.
Some of the incidents and characters in the spoof rock documentary This Is Spinal Tap are based on Black Sabbath.