Hard Rock

Hard rock is blues rock with the weight shifted forward. The riff becomes the song’s engine, distortion becomes a default color, the drums grow heavier, and the singer has to cut through the whole machine. It is still close enough to the blues to quote it directly, but the experience is different: less club, more impact.

Led Zeppelin are the central early case: a band built from blues repertoire, session-player precision and enormous live dynamics. The Who supplied volume, power chords and theatrical violence; Hendrix supplied the guitar vocabulary that made distortion expressive rather than merely loud. From this zone, heavy metal will eventually split off as a more codified, darker and more extreme branch.

In the web, hard rock is the heavier descendant of British blues and blues rock, with psychedelic rock feeding its scale, texture and permission to leave the three-minute single behind.