During the 1960s, volume was explored to greater degrees than ever before. Bands such as the Who played at ear shattering levels; the Velvet Underground recorded way into the red; and Jimi Hendrix turned the blues upside-down with his feedback-laden solos and astonishing musicianship. Rock 'n' roll had discovered its bombastic side, and hard rock was the result. Quintessential hard-rock acts Led Zeppelin and Black Sabbath gave the music a dark and ominous edge, while the equally quintessential Thin Lizzy and Cheap Trick kept it fun. Heavy metal was introduced in the '70s, taking the bombast of hard rock even further while stripping the music of most of its swing. With pummeling rhythms and rapid-fire riffs, heavy metal is more menacing than its blues-oriented cousin. Despite being a rigid style, however, heavy metal has evolved into a surprisingly wide range of subgenres, including the rap metal of Rage Against the Machine and the death metal of Norway's Dimmu Borgir.

Notable Artists: Black Sabbath, Led Zeppelin, Motorhead, Metallica, AC/DC