Rock

Rock at its baseline is a four-piece: two electric guitars, bass, drums, vocal. Tempos run 100-170 BPM; drummers anchor a backbeat with snare on 2 and 4, bass shadows the guitar's root notes, and the song is built around a hook-riff that returns between verses. Vocals are unrestricted — speech-like in the verse, belted in the chorus, screamed at the climax. Verse/chorus/bridge structures dominate, though prog and hard rock stretch the form. What unites the genre across eras is the sound of humans playing physical instruments in a room.

Rock and roll cohered in the American South circa 1955 — Elvis Presley, Chuck Berry, and Little Richard speeding up blues, country, and R&B for a teenage audience. The British Invasion of 1964 (The Beatles, The Rolling Stones, The Who) shortened the name to 'rock' and broadened the palette. The 1970s super-sized it: Led Zeppelin, Pink Floyd, Deep Purple, Queen. Punk reset it in 1977, and Nirvana, Radiohead, and the Red Hot Chili Peppers redefined it in the 1990s. After 2000 the commercial center of pop shifted to hip-hop, but the form keeps reproducing itself.

The first thing to hear is the riff — how memorable, how physical. Then the handoff between vocal hook and guitar solo, and the way the bridge holds tension before the final chorus releases it. Guitar-and-amp pairings color the sound: a Telecaster through a Vox sounds bright and chimy; a Les Paul through a Marshall sounds thick and saturated; an SG through an AC30 gives the smoky Pink Floyd low end. Drummers' fills between sections are signatures — Bonham, Moon, and Grohl each fill a bar differently.

Start with The Rolling Stones' '(I Can't Get No) Satisfaction' (1965) for the riff that demonstrates the form. For an album, Led Zeppelin IV (1971) compresses most of what 1970s rock did into 42 minutes; for the 1990s, Nirvana's 'Nevermind' (1991).

'Rock and roll' was Black slang for sex in 1920s blues recordings. Cleveland DJ Alan Freed adopted the phrase in 1951 to package Black R&B records for a white teenage radio audience — the moment the term went from euphemism to genre name.