Labeling music is meaningless for precisionists, frustrating for musicians, but fun for writers. This section is for all you cowards who will find most of this music much easier to read about than to listen to.
RAPCORE/NU-METAL: You riff, you rap, you wear a baseball cap. Maybe you've got a DJ, maybe not, but if you don't have a groove that kills, fergit it. Onstage, you bend over as far as you can without falling down. Your lyrics work your personal beefs, but you're not a wimp like those grunge guys cuz you don't bother much with melodies. If kids perceive you've got a figurehead with special parental-irritation value (Fred Durst of Limp Bizkit; Zack de la Rocha, formerly of Rage Against the Machine), you've got potential for bigbucks intake. Ultimately, it's all the Red Hot Chili Peppers' fault.
STONER METAL: Low, slow and totally blunted. Guitars tuned slack enough that a cop's neck will fit under the strings; occasional solos floating up like hash smoke; drums slogging away with comforting inevitability. The logical devolution of Black Sabbath. Electric Wizard, Spirit Caravan, Sea of Green.
SLUDGE/DOOM: It'd be stoner metal except there are no acid-damaged solos and there's not so much groove; it's just gloriously bleak, atmospheric and depressing. Less drugs to fall back on, too, unless you count Prozac. Pass the razor! Neurosis, Cathedral, Isis.
SPEED METAL: The guitarist requires a solid-state amp with distortion knob turned to 10 so his ax virtually becomes a percussion instrument. If you can hear the individual beats of the double kick drums, it's too slow. Vox like a raven shrieking. Current accelerators: Anal Cunt, Agoraphobic Nosebleed, Pig Destroyer.
GRINDCORE: Way back in the '80s, Napalm Death set a standard of unlistenability that many have strained to match since. Groaning “Cookie Monster” vocals and putrescence-related themes (see Death Metal), riffs like a machinist on meth, tin-can drums. Who's the Slayer and who are the slain? Cephalic Carnage, Nasum, Benumb.
THRASH: Speedy! Grindy! But way more dynamic, complicated start-stop compositions like a time-lapse video of L.A. traffic, plus crazy changes of time signature and tempo. Thrash is a venerable offshoot of speed-punk, with bands like Pantera stubbornly unchanged for generations. Nu-skool avatars: Shadows Fall, The Haunted, Soilwork.
HARDCORE: Hardnfast for doctrine-dogmatists only; no nihilists need apply. Christians, Hare Krishnas, vegan eco-warriors and even hatecore proselytizers, come on in! Coalesce, Drowningman, Glassjaw.
DEATH METAL: Vox like a sumo dude's belch after 11 double Tommyburgers. Can't understand the words to tunes like Cannibal Corpse's “Devoured by Vermin”? Is that a problem? Midtempo meat-cleaver guitar riffs. Classic drum fills revealing suppressed Zep envy. Fashion: jeans and T's. Preferred mode of expiration: exotic parasitic infestation. Morbid Angel, Dying Fetus, Six Feet Under.
BLACK METAL: No African implications — this is power-prog with pancake. Combines a yearning for the melodic dignity of a symphony orchestra or a Bach fugue (keyboards allowed!) with a heartfelt desire to smash your face in. Lifestyle is important; max respect gained if you can be convicted of murder like Christien Vikernes of the Norwegian band Burzum, or at least have a church-burning under your belt. Those who think Scandinavia is civilized should know that it's Black Metal Central. Fashion: fangs, chain-mail shirts, black-leather pants. Mayhem, Emperor, Cradle of Filth.
MATH METAL: Posit the brainy, intricate tendencies of a Joe Satriani, double the speed, subtract all interest in traditional melody, and it factors out to this: calculus geeks who aren't too withdrawn to slash your tires if you throw spitballs at them. Meshuggah, Cryptopsy, Goreguts.
PROG/POWER METAL: Damsels, dragons and knights are still around, as are baroque guitar solos and virtuosic vocal wailing. Rhapsody, Hammerfall, Blind Guardian.
ETHNO METAL: Why the hell not stick some of your native country's instruments, folk styles and mythologies into your metal? Puerto Rico's Puya, Brazil's Soulfly and Finland's Amorphis did it, and nobody took their drugs away.
MISCELLANEOUS AVANT-HYBRID METAL: Some bands hate definitions so much that they change their sound with each record just to confuse jerks like us. Or else they're creative. Candiria, Melvins, Mr. Bungle.