Gonzo rock critic Lester Bangs, in The Rolling Stone Illustrated History of Rock & Roll (2nd edition), has provided one of the more colorful--and accurate--definitions of the genre:
As its detrators have always claimed, heavy-metal rock is nothing more than a bunch
of noise; it is not music, it's distortion--and that is precisely why its adherents find it
appealing....it's noise is created by electric guitars, filtered through an array of warping
devices from fuzztone to wah-wah, cranked several decibels past the pain threshold,
loud enough to rebound off the walls of the biggest arenas anywhere. Add the aural
image of a battering ram, and you've got a pretty good picture of what heavy metal
He adds that the style also includes "brutal guitars, equally thunderous slabs of think-thudding bass, and the obligatory extended drum solo in concert."
The British hard rock bands of the mid-1960s anticipated the genre, both its sound and attitude. Notable pioneers included the Who (e.g., "My Generation," "I Can See For Miles") and the Yardbirds alums Eric Clapton, Jeff Beck, and Jimmy Page, all masters of fuzztone-and-feedback drenched onslaughts. Jimi Hendrix provided the link between these antecedents and the earliest practitioners of the style proper via his guitar pyrotechnics and banshee vocals.
While California bands--specifically, renegades from psychedelia (e.g., Blue Cheer) and acid rock (e.g., Iron Butterfly)--were playing heavy metal, or something close to it, by early 1968, and yet another stateside group provided the name itself (Steppenwolf's line from "Born to Be Wild": "heavy metal thunder") that same year, the British scene proved more prolific at the outset of the 1970s. Three divergent movements quickly emerged there, including (1) post-psychedelic hard rock, exemplified by the cinematic guitar stylings and evocative lyric imagery of Led Zeppelin, Black Sabbath, and Robin Trower; (2) working class rock, built on predictable heavy riffs and the cultivation of a "bad boy" image (e.g., Deep Purple, Bad Company); and (3) aristocratic Anglo-metal, featuring the glam dress of acts like Queen and Sweet.
During this time, American bands projected a distinctly working class image; e.g., Cactus, Mountain, the Frost, Aerosmith, Kiss, Grand Funk Railroad, and Bachman-Turner Overdrive (Canada). Two subdivisions grew out of this school: American revolutionary bands, who considered rock to represent an instrument of social change (e.g., MC5); and boogie bands, dedicated to simple riffing for the sake of partying (e.g., Black Oak Arkansas, ZZ Top). In reaction to these subgenres, yet another offshoot--the American Deviates--emerged. Generally inspired by the Velvet Underground, its practitioners (e.g., Iggy and the Stooges, Alice Cooper, Blue Oyster Cult) were dedicated to, in Bangs' words, "The reinforcement of whatever vestiges of primal infantalism have managed to survive into adolescence, and the glorification of adolescence as the Time of Your Life."
By the late 1970s the genre had fallen into middle-of-the-road respectibility largely due to the effort of artists such as Toto, Triumph, Foreigner, Journey, Heart, Van Halen, and Ted Nugent. What little flair and freshness remained was appropriated by two newly emerging genres, speed metal and punk rock. The foremost practitioners of the former—e.g., Metallica, Megadeath, Godflesh—have remained viable throughout the 1990s, grudgingly appropriating the trappings of the more progressive hard rockers. Punk, however, proved to be the more important of the two, stripping heavy metal down, speeding it up, and providing some lyric content beyond the customary macho posturing.
The riot grrrl movement of the early 1990s also borrowed heavily from heavy metal. Notable distaff bands from the period included Bikini Kill and L7. Groups such as Luscious Jackson and Fluffy opted for a sound more closely aligned with the pop mainstream.
The late 1990s have seen a revival of the more traditional exponents of the genre. Reformed first generation bands such as Black Sabbath, Alice Cooper, and Grand Funk Railroad have again found success via both recordings and the stage; third generation copy bands such as Poison, Cinderella, Warrant, and Motley Crue have also enjoyed a commercial resurgence. In short, heavy metal has continued to thrive, a genre secure in the fact that its primary audience--teenaged males--will always derive immense sustenance from its manic energy and rebellious attitude.