Black Sabbath is credited with creating heavy metal. The success of their first two albums - Black Sabbath and Paranoid - marked a paradigm shift in the world of rock. Not until Black Sabbath upended the music scene did the term "heavy metal" enter the popular vocabulary to describe the denser, more thunderous offshoot of rock over which they presided. With their riff-based songs, extreme volume, and dark, demonic subject matter, Black Sabbath embodied key aspects of the heavy-metal aesthetic. Yet in their own words, they saw themselves as a "heavy underground" band. That term denoted both the intensity of their music and the network of fans who found them long before critics and the music industry took notice.
Black Sabbath released a remarkable four genre-defining albums (Black Sabbath, Paranoid, Master of Reality, Vol. 4) in just a two-year period from 1970-1972 while also touring at a ceaseless pace. The group's fifth album, Sabbath Bloody Sabbath (1973), showed further signs of growth and experimentation, and the title track ranks among their finest moments. As a totality, it comes closest to equaling their early masterpiece, Paranoid. The group wrote and rehearsed the material for Sabbath Bloody Sabbath at a castle in Wales that they claimed was haunted, further fueling their music's unnerving vibe at a time when the group was testing its own mental and physical limits.