Most people who encountered Quiet Riot’s 1983 hit Metal Health—one of the first heavy metal albums to become a mainstream phenomenon—likely didn’t realise that, by the time the record topped the US charts, the band had already been around for about 10 years. The group’s first two albums—which featured future Ozzy Osbourne guitar hero Randy Rhoads—had only been released in Japan, and by 1981, the band had actually broken up, only to reform with a new line-up a year later. In the meantime, metal had developed from its early years as a bruising, antisocial response to mainstream pop into something that aggregated loud guitars, obnoxious lyrics, a lewd sense of showmanship and a post-Beatles reverence for big, catchy hooks. This was especially true of the scene in Los Angeles, home to Van Halen, Mötley Crüe, Ratt, W.A.S.P.—and, of course, Quiet Riot. The fact that the band’s most enduring hit, “Cum On Feel the Noize”, was a cover of a song by 1970s British glam-rock band Slade was telling: Metal Health wasn’t Iron Maiden or even Judas Priest—it was Thin Lizzy with more distortion (“Slick Black Cadillac”), or AC/DC with bigger, better hair (“Metal Health”). The album even offered a prototype for the metal power ballad: “Love’s a Bitch”. In the years after Metal Health’s release, metal branched off in two different directions: The glammy, even more pop-friendly sound of so-called hair metal, and the hardcore-influenced sound of thrash bands like Metallica, Slayer and Megadeth (before Guns N’ Roses managed to split the difference). Both sides sold wildly well, and, like the evolution of hip-hop, your preference of one over the other mostly had to do with genre politics. But none of it could have existed without Metal Health.