Originally Posted by
binnie
'Metalcore' is a term which referes to a sub-genre of metal. To describe the sound, it is essentially a cross over between metal and hardcore - imagine classic metal elements (duel-guitar melodies, thrash-riffing) with hardcore beatdowns and vocal styles. Usually, the verses of songs will be in the cookie-monster style, and the chorus will be sung. Some bands even have two singers for that reason.
Essentially, the genre was kickstarted by Killswitch Engage with their second record, 'Alive Or Just Breathing'. It's a monster of a record, and I'd recommend anyone who loves metal to check it out (along with 'The End Of Heartache' and and 'Disarm The Descent'). That essentially killed Nu Metal (Korn, Limp Bizkit). Since then, most mainstream metal (i.e. not Death Metal/ Black Metal or grindcore) has sounded very, very close to that template.
Avenged Sevenfold were certainly a metalcore band when they started in the early 00s. Their sound was always more expansive, however, and often involved quite a bit of prog. Albums like 'Waking The Fallen' and 'City Of Evil' were exciting, innovative even. Their new stuff has really moved away from metalcore into a more classic metal sound - if I was been churlish, I'd point out that they've essentially parodied GNR/Metallica/AC/DC in order to up their commerical status. Their early work is cool, however, and they've definitely got a much wider musical palette than most of their generation.
Other metalcore bands: As I Lay Dying, The Devil Wears Prada, Bury Tomorrow, All That Remains, August Burns Red (often excellent), Parkway Drive.
NB: Dillinger Escape Plan are not metalcore. They are one of those bands that is impossible to classify, and truly innovative. Their music is absolutely insane - not for everyone by any stretch of the imagination, but they're one of the best heavy bands of the last 15 years.