Heavy metal (or simply metal) is a genre of rock music[3][4] that developed in the late 1960s and early 1970s, largely in the United Kingdom and the United States.[5] With roots in blues rock, psychedelic rock, and acid rock,[6] the bands that created heavy metal developed a thick, massive sound, characterized by highly amplified distortion, extended guitar solos, emphatic beats, and overall loudness. The genre’s lyrics and performance styles are sometimes associated with aggression and machismo.[6]

In 1968, three of the genre’s most famous pioneers, Led Zeppelin, Black Sabbath and Deep Purple were founded.[7] Though they came to attract wide audiences, they were often derided by critics. Following the blueprint laid down by Led Zeppelin and Black Sabbath, several American bands modified heavy metal into more accessible forms during the 1970s: the raw, sleazy sound and outrageous stage shows of Alice Cooper and Kiss; the blues-rooted rock of Aerosmith; and the flashy guitar leads and wild party rock of Van Halen.[8] During the mid-1970s, Judas Priest helped spur the genre’s evolution by discarding much of its blues influence;[9][10] Motörhead introduced a punk rock sensibility and an increasing emphasis on speed. Beginning in the late 1970s, bands in the new wave of British heavy metal such as Iron Maiden and Def Leppard followed in a similar vein. Before the end of the decade, heavy metal fans became known as “metalheads” or “headbangers”.

During the 1980s, glam metal became popular with groups such as Bon Jovi and Mötley Crüe. Underground scenes produced an array of more aggressive styles: thrash metal broke into the mainstream with bands such as Metallica, Slayer, Megadeth, and Anthrax, while other extreme subgenres of heavy metal such as death metal and black metal remain subcultural phenomena. Since the mid-1990s popular styles have further expanded the definition of the genre. These include groove metal and nu metal, the latter of which often incorporates elements of grunge and hip hop.