Map of Metal

Heavy metal (often referred to simply as metal) is a genre of rock music that developed in the late 1960s and early 1970s, largely in the United Kingdom and the United States. With roots in blues-rock and psychedelic rock, the bands that created heavy metal developed a thick, massive sound, characterized by highly amplified distortion, extended guitar solos, emphatic beats, and overall loudness. Heavy metal lyrics and performance styles are generally associated with masculinity and machismo. 

In the late 1960s the term heavy metal was used interchangeably with hard rock, but gradually began to be used to describe music played with even more volume and intensity. While hard rock maintained a bluesy rock and roll identity, including some swing in the back beat and riffs that tended to outline chord progressions in their hooks, heavy metal's riffs often functioned as stand-alone melodies and had no swing in them. 

Led Zeppelin defined central aspects of the emerging genre, with Page's highly distorted guitar style and singer Robert Plant's dramatic, wailing vocals. Other bands, with a more consistently heavy, "purely" metal sound, would prove equally important in codifying the genre. The 1970 releases by Black Sabbath (Black Sabbath and Paranoid) were crucial in this regard. Black Sabbath had developed a particularly heavy sound in part due to an industrial accident guitarist Tony Iommi suffered before cofounding the band. Unable to play normally, Iommi had to tune his guitar down for easier fretting and rely on power chords with their relatively simple fingering. Deep Purple had fluctuated between styles in its early years, but by 1969 vocalist Ian Gillan and guitarist Ritchie Blackmore had led the band toward the developing heavy metal style. 

Judas Priest arrived to unify and amplify the heavy metal aesthetic from hard rock's sonic palette. For the first time, heavy metal became a true genre unto itself. Though Judas Priest did not have a top 40 album in the U.S. until 1980, for many it was the definitive post-Sabbath heavy metal band; its twin-guitar attack, featuring rapid tempos and a nonbluesy, more cleanly metallic sound, was a major influence on later acts. 

Many subgenres of heavy metal developed outside of the commercial mainstream during and after the 1980s.