Classic rock is the bedrock of everything that came after. Rooted in the blues explosion of the 1960s and the stadium ambitions of the 1970s, it defined what rock music sounds like: big guitars, bigger choruses, and the idea that a band could fill an arena with nothing but volume and conviction.

From the British Invasion acts who rewired American blues through Marshall stacks to the Southern rockers who turned it into something sweatier and more dangerous, classic rock established the vocabulary every subsequent subgenre either built on or rebelled against.

Heavy metal took the heaviest elements of blues rock and hard rock and pushed them past the point of no return. Born in the late 1960s in the industrial heartland of Birmingham, England, it turned distortion into an art form and volume into a philosophical statement.

From Black Sabbath's doom-laden riffs to Iron Maiden's galloping twin guitars to Metallica's precision thrash, metal has continuously evolved while maintaining its core identity: heavy, aggressive, technically demanding, and utterly uncompromising.

Punk was a Molotov cocktail thrown at the bloated prog-rock establishment of the mid-1970s. It stripped rock down to its barest essentials, three chords, two minutes, one message, and proved that attitude mattered more than technique.

From the Ramones' bubblegum velocity to the Sex Pistols' calculated chaos to Black Flag's unhinged aggression, punk's influence extends far beyond its own genre boundaries. It created the DIY infrastructure that alternative music still runs on.

Alternative rock was never one sound. It was everything that didn't fit the hair metal and pop paradigm of the 1980s. College radio stations and independent labels built an underground network that eventually became too big to ignore.

From R.E.M.'s jangly mystery to Pixies' loud-quiet-loud dynamics to Radiohead's progressive deconstruction of rock itself, alternative proved that commercial success and artistic ambition weren't mutually exclusive, even if that was never really the point.

Grunge fused punk's aggression with metal's weight and wrapped it in Pacific Northwest rain and existential dread. For a brief, incandescent moment in the early 1990s, it was the biggest thing in music, then it burned itself out, because that's what grunge does.

What started in Seattle's basements and dive bars, Sub Pop singles, all-ages shows at the Crocodile, became a cultural earthquake that buried hair metal overnight and proved that mainstream audiences were hungry for something real.

Progressive rock asked: what if rock musicians had classical ambitions? The result was sprawling concept albums, irregular time signatures, virtuosic performances, and the conviction that a song could be twenty minutes long if it needed to be.

From King Crimson's dissonant fury to Yes's symphonic grandeur to Pink Floyd's cinematic soundscapes, prog pushed rock's boundaries further than anyone thought possible, and drew punk's ire precisely because of it.

Indie rock started as a description of a business model, bands on independent labels, and became a genre defined by its refusal to be easily defined. Lo-fi aesthetics, literary lyrics, angular guitars, and a commitment to doing things on your own terms.

From Pavement's slack genius to the Strokes' calculated cool to Arctic Monkeys' sharp-tongued storytelling, indie rock proved that rock music could evolve without corporate backing.

Hard rock is the direct ancestor of heavy metal and the louder, meaner sibling of classic rock. It took blues rock's foundation and cranked every dial past ten: more distortion, more volume, more swagger.

From Led Zeppelin's crushing riffs to Van Halen's acrobatic fretwork to Guns N' Roses' dangerous glamour, hard rock has always been about impact. It's the sound of a Marshall stack pushed to its limits in a room full of people who came to feel it in their chest.

Post-punk didn't reject punk. It took punk's permission slip and ran somewhere darker, stranger, and more ambitious. While punk said anyone could start a band, post-punk asked what those bands might sound like if they listened to Kraftwerk, dub reggae, and avant-garde film scores instead of Chuck Berry. The guitars got colder, the bass moved to the front of the mix, drum machines replaced thrashing kits, and vocalists traded shouting for something more unsettling: murmured, chanted, or delivered with theatrical detachment.

The movement emerged in the late 1970s primarily in the UK, where the initial adrenaline rush of punk was already fading into formula. Bands like Joy Division, Wire, and Siouxsie and the Banshees kept punk's DIY ethos and rejection of rock-star posturing but abandoned its musical limitations. They drew freely from electronic music, funk, disco, and the sonic experiments of producers like Martin Hannett and Dennis Bovell, creating records that sounded nothing like the Ramones or the Pistols but couldn't have existed without them.

Post-punk's influence is so deep that it's essentially invisible. It runs through goth, industrial, shoegaze, Britpop, indie rock, darkwave, and the 2000s post-punk revival (Interpol, Editors, She Wants Revenge) like underground plumbing. The genre's willingness to be cold, intellectual, and emotionally opaque gave rock music a new emotional register that it still draws from today. If punk was a fist, post-punk was an open hand reaching for something it couldn't quite name.