Black Sabbath And Paranoid (1970–1971)

Black Sabbath were signed to Philips Records in December 1969, and released their first single, "Evil Woman" through Philips subsidiary Fontana Records in January 1970. Later releases were handled by Philips' newly formed progressive rock label, Vertigo Records. Although the single failed to chart, the band were afforded two days of studio time in late January to record their debut album with producer Rodger Bain. Iommi recalls recording live: "We thought 'We have two days to do it and one of the days is mixing.' So we played live. Ozzy was singing at the same time, we just put him in a separate booth and off we went. We never had a second run of most of the stuff." The eponymous Black Sabbath was released on Friday the 13th, February 1970. The album reached number 8 in the UK Albums Chart, and following its US release in May 1970 by Warner Bros. Records, the album reached number 23 on the Billboard 200, where it remained for over a year. While the album was a commercial success, it was widely panned by critics, with Lester Bangs of Rolling Stone dismissing the album as "discordant jams with bass and guitar reeling like velocitised speedfreaks all over each other's musical perimeters, yet never quite finding synch". It sold in substantial numbers despite being panned, giving the band their first mainstream exposure. It has since been certified platinum in both US by the Recording Industry Association of America (RIAA) and in the UK by British Phonographic Industry (BPI).

To capitalise on their chart success in the US, the band quickly returned to the studio in June 1970, just four months after Black Sabbath was released. The new album was initially set to be named War Pigs after the song "War Pigs", which was critical of the Vietnam War. However Warner changed the title of the album to Paranoid, fearing backlash by supporters of the Vietnam War. The album's lead-off single "Paranoid" was written in the studio at the last minute. As Bill Ward explains: "We didn't have enough songs for the album, and Tony just played the (Paranoid) guitar lick and that was it. It took twenty, twenty-five minutes from top to bottom." The single was released ahead of the album in September 1970 and reached number four on the UK charts, remaining Black Sabbath's only top ten hit.

Black Sabbath released their second full-length album, Paranoid in the UK in October 1970. Pushed by the success of the "Paranoid" single, the album hit number one in the UK. The US release was held until January 1971, as the Black Sabbath album was still on the charts at the time of Paranoid's UK release. The album broke into the top ten in the US in March 1971, and would go on to sell four million copies in the US, with virtually no radio airplay. The album was again panned by rock critics of the era, but modern-day reviewers such as AllMusic's Steve Huey cite Paranoid as "one of the greatest and most influential heavy metal albums of all time", which "defined the sound and style of heavy metal more than any other record in rock history". In 2003, the album was ranked number 130 on Rolling Stone magazine's list of the 500 greatest albums of all time. Paranoid's chart success allowed the band to tour the US for the first time in December 1970, which spawned the release of the album's second single "Iron Man". Although the single failed to reach the top 40, "Iron Man" remains one of Black Sabbath's most popular songs, as well as the bands highest charting US single until 1998's "Psycho Man".