In an age where alternative rock bands fill stadiums and ascend the pop charts, it begs the question: alternative to what? Early on, the alternative movement was a reaction to the commercial excesses of mainstream rock. Alt-rock instead brought quirky hooks, a do-it-yourself ethos, deeply personal songwriting, and genre-bending adventures to audiences hungry for something different. Although it truly exploded in the early ’90s, the roots of alternative rock started with the punk revolt of the late ’70s, when bands like the Ramones and the Sex Pistols proved that just about anyone could get up onstage or make a record. Throughout the ’80s, an international network of under-the-radar bands developed, nurtured by college radio DJs and small clubs. While hardcore kept the traditional loud-and-fast sound of punk alive, many newer bands had their own distinctive styles: R.E.M.'s jangling folk-influenced rock, Sonic Youth's dissonant noise, The Cure's epic gloom, Pixies' whisper-to-a-scream dynamics, New Order's electronic grooves. North of the border, an earthier emerged, from the paisley-patterned pop of The Grapes of Wrath to the narcotic blues of the Cowboy Junkies.

Eventually, these bands were dubbed alternative rock, thanks to their left-of-center sounds and attitudes. By the early ’90s, though, grunge bands like Nirvana and Pearl Jam were combining punk’s raw energy with classic hard-rock hooks and entered the pop charts. Suddenly, other alternative heroes like Red Hot Chili Peppers and Soundgarden found massive audiences. Over the next decade, alt-rock bands of various subgenres introduced a whole generation of young rockers to punk (Green Day), hip-hop (Rage Against the Machine), industrial (Nine Inch Nails), art rock (Radiohead), power pop (Sloan), psychedelia (The Flaming Lips), metal (Tool), the British Invasion (Oasis), electronica (The Prodigy), and much more. On Canadian radio, the line separating mainstream and alternative was further fudged by artists—Moist, Our Lady Peace, The Tea Party, Matthew Good— who exuded the angst of grunge, but the slickness of arena acts. By the 21st century, alternative rock had grown popular enough to let bands like Foo Fighters and Coldplay sell out stadiums in minutes. At the same time, the anything-goes spirit of alternative rock remained alive and well, with newer bands embracing garage rock (The White Stripes), emo (Paramore), symphonic pomp (Arcade Fire), soft pop (Feist) and new wave (The Killers).