Since forming in 1981, Metallica has led the way in redefining the stylistic boundaries of heavy metal. While incorporating elements of punk and hardcore, the band has brought a greater energy, sonic diversity (ranging from visceral thrash and riff-heavy grinders to roots-derived rockers and melodramatic ballads), and attention to songcraft, most notably appealing melodic hooks and strong lyrics, to what was perceived as a rather tired, moribund genre. Guided by drummer/composer Lars Ulrich and lead vocalist/rhythm guitarist/composer James Hetfield—the constants in the constantly shifting lineup of the early 1980s—Metallica emerged as one of the premier American bands on the strength...