Metal
Metal pushed Rock's volume, distortion, and intensity to their structural extreme, building a classification defined by heavily amplified guitar architecture, aggressive rhythmic drive, and vocal styles ranging from melodic to harshly extreme.
Traditional
The moment Rock's riff stopped serving the song and became the song. Black Sabbath didn't set out to invent a genre; they set out to make music that sounded like the feeling of standing next to something dangerous. They succeeded, and everything in Metal traces its lineage directly back to that sound. The weight, the darkness, and the deliberate heaviness of tone signal something Hard Rock never quite intended. Era independence applies here too — a modern band deliberately working in this original Sabbath/Priest/Maiden idiom classifies as Traditional Metal regardless of recording date, the structural mode is what matters, not the calendar.
Black Sabbath · Judas Priest · Iron Maiden
Power
Metal made triumphant. Power Metal took Traditional Metal's riff architecture and pointed it upward — melodic, anthemic, and possessed of a heroic grandeur that Hard Rock approached occasionally and Power Metal pursued as its primary artistic destination. The vocals are operatic, the tempos are driving, and feeling genuinely, unironically epic is a legitimate artistic destination.
Queensrÿche · Helloween · Blind Guardian
Thrash
Punk aggression applied to Metal riff architecture. Thrash combined Punk's speed and anger with Metal's riff sophistication and technical ambition. The palm-muted speed-picked riff became the defining structural unit. Metallica's first four albums are the essential documents of what Thrash accomplished at its peak.
Metallica · Slayer · Megadeth
Death
The complete abandonment of everything Blues ever contributed to Rock and Metal. The riffs are chromatic and atonal, moving through intervals Western ears are trained to find deeply uncomfortable. The vocals abandon melody altogether in favor of a guttural delivery functioning more as a percussive instrument. This is Metal that has followed its own internal logic to its furthest possible conclusion.
Death · Cannibal Corpse · Morbid Angel
Black
Where Death Metal pursued technical extremity, Black Metal pursued atmosphere — cold, vast, and deliberately primitive. The tremolo-picked guitar creates a wall of harmonic stasis, the vocals are shrieked rather than growled, and the raw production is a structural choice. Black Metal sounds like it was recorded in a Norwegian forest in winter.
Mayhem · Burzum · Emperor
Doom
Heaviness achieved through weight and patience rather than speed. The tempos are glacial, the riffs resolve with a deliberate reluctance that makes each chord change feel like a physical event. Where Thrash hits you and Death Metal overwhelms you, Doom Metal surrounds you and waits.
Black Sabbath · Candlemass · Electric Wizard
Progressive
Metal: Progressive builds its complexity from the riff itself. Remove the riff and there is no composition underneath — the composition and the riff are the same thing. This is why Rush is Rock: Progressive and Dream Theater is Metal: Progressive, and why both placements are correct.
Dream Theater · Tool · Opeth
Groove/Modern
The riff made hypnotic rather than aggressive. Groove Metal syncopated the riff — slowing the tempo, emphasizing the rhythmic pocket, discovering that a riff played with enough mid-tempo swagger could be as physically compelling as anything Thrash accomplished at twice the speed. The most likely corner of Metal to convert a listener who thought they didn't like Metal.
Pantera · Lamb of God · Marilyn Manson