Nu-metal is an offshoot rock sub-genre.
It consists of bands with a rap hint on them which you oftenly don't notice, this sub-genre became 'alive' in the 90's.. when bands like rage against the machine, deftones, korn, etc. are rising above the charts.
Bands started to start their own Nu trend.. such as wearing coveralls, 7-string light-distorted guitars, snare-cymbal-snare drum playing, etc.
Nu-metal pros:
They're popular as f*ck!
Nu-metal cons:
They make fun of popular music especially Britney Spears and any boyband, yet their music sells equally as them.
Their guitar players do not play solos, such a shame to the world of true Metal.
Their bass players use the "slap and pop" playing style.
Uses coveralls, ie-- jumpsuits, random masks, anonymous names, face paints. The black metal genre is an exception on the face paint, they put it on themselves in attempt to add the evilness that is in them, besides for the fact that Black Metal is an Elit genre and has a straight-style line.
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but the Nu-metal 'scene' is now dying off, most of the bands that are getting played/played out on radio/tv are the type of metalcore/hardcore/emo/etc. type. and in a couple of years, it will be worse.