While earlier tracks by bands such as Led Zeppelin and Iron Butterfly still cause debates over whether they’re hard rock or heavy metal, Black Sabbath’s debut album and its title track are undeniably the evil, distorted, and aggressive development of hard rock, blues rock, and psychedelic rock which would later be dubbed heavy metal music. Its slow, heavy sound until the outro is a precursor to the heavy metal subgenre known as doom metal.

Rob Halford—vocalist of Judas Priest—described “Black Sabbath” as “the most evil track ever that’s been written,” a title now commonly repeated and reaffirmed by fans.

A demo version with an additional third verse was released in 1997.