Black Sabbath has sold over 70 million records worldwide, including a RIAA-certified 15 million in the U.S. They are one of the most influential heavy metal bands of all time. The band helped to create the genre with ground-breaking releases such as Paranoid (1970), an album that Rolling Stone magazine said "changed music forever", and called the band "the Beatles of heavy metal".Time Magazine called Paranoid "the birthplace of heavy metal", placing it in their Top 100 Albums of All Time.Rolling Stone magazine ranked Black Sabbath number 85 in their list of the "100 Greatest Artists of All Time. MTV placed Black Sabbath at number one on their Top Ten Heavy Metal Bands and VH1 placed them at number two on their list of the 100 Greatest Artists of Hard Rock. VH1 ranked Black Sabbath's "Iron Man" the number one song on their 40 Greatest Metal Songs countdown. AllMusic's William Ruhlmann said:
Black Sabbath has 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 emphasising 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.
According to Rolling Stone's Holly George-Warren, "Black Sabbath was the heavy metal king of the 70s." Although initially "despised by rock critics and ignored by radio programmers", the group sold more than 8 million albums by the end of that decade.
Metallica's Lars Ulrich, who, along with bandmate James Hetfield inducted Black Sabbath into the Rock and Roll Hall of Fame in 2006, said "Black Sabbath is and always will be synonymous with heavy metal", while Hetfield said "Sabbath got me started on all that evil-sounding shit, and it's stuck with me. Tony Iommi is the king of the heavy riff." former Guns N' Roses guitarist Slash said of the Paranoid album: "There's just something about that whole record that, when you're a kid and you're turned onto it, it's like a whole different world. It just opens up your mind to another dimension...Paranoid is the whole Sabbath experience; very indicative of what Sabbath meant at the time. Tony's playing style—doesn't matter whether it's off Paranoid or if it's off Heaven and Hell—it's very distinctive."Anthrax guitarist Scott Ian said "I always get the question in every interview I do, 'What are your top five metal albums?' I make it easy for myself and always say the first five Sabbath albums."
Lamb of God's Chris Adler said: "If anybody who plays heavy metal says that they weren't influenced by Black Sabbath's music, then I think that they're lying to you. I think all heavy metal music was, in some way, influenced by what Black Sabbath did." Judas Priest vocalist Rob Halford commented: "They were and still are a groundbreaking band..you can put on the first Black Sabbath album and it still sounds as fresh today as it did 30-odd years ago. And that's because great music has a timeless ability: To me, Sabbath are in the same league as the Beatles or Mozart. They're on the leading edge of something extraordinary." On Black Sabbath's standing, Rage Against the Machine guitarist Tom Morello states: "The heaviest, scariest, coolest riffs and the apocalyptic Ozzy wail are without peer. You can hear the despair and menace of the working-class Birmingham streets they came from in every kick-ass, evil groove. Their arrival ground hippy, flower-power psychedelia to a pulp and set the standard for all heavy bands to come."Phil Anselmo of Pantera and Down stated that "Only a fool would leave out what Black Sabbath brought to the heavy metal genre".
Tony Iommi has been credited as the pioneer of lighter gauge guitar strings. The tips of his fingers were severed in a steel factory, and while using thimbles (artificial finger tips) he found that standard guitar strings were too difficult to bend and play. He found that there was only one size of strings available, so after years with Sabbath he had strings custom made.
Culturally, Black Sabbath have exerted a huge influence in both television and literature and have in many cases become synonymous with heavy metal. In the film Almost Famous, Lester Bangs gives the protagonist an assignment to cover the band (plot point one) with the immortal line: 'Give me 500 words on Black Sabbath'. Contemporary music and arts publication Trebuchet Magazine has put this to practice by asking all new writers to write a short piece (500 words) on Black Sabbath as a means of proving their creativity and voice on a well documented subject.