The sound of NU metal was definitely the new wine at the turn of the millennium. It remains controversial among more traditional metal fans but this experimental, creative and highly successful subgenre is a very important part of the history of heavy metal.
Different alternative forms of rock and metal swept the shores of the music world at the beginning of the 90's. The grunge wave retreated pretty soon, after just too much commercial exposure and the tragic early death of grunge icon Kurt Cobain but the grunge ethos created a long lasting change. As a result the heavy metal scene was a bit confused in the 90's. Grunge and alternative metal had basically turned the metal world upside down and more traditional types of metal were having a hard time. The growing power metal subgenre had started to revitalize the traditional elements of heavy metal but there was more to come from the alternative world.
Some alternative bands started to combine the distorted and aggressive guitar sound from heavy metal with rap, hip-hop and and elements from industrial rock. The new music was labelled NU metal.
There were some early signs with Faith No More's hit "Epic" (1990), thrash metal band Anthrax' collaboration with hip hop act Public Enemy on "Bring the Noise" (1991) and the rap metal sound of Rage Against the Machine (1992). Also, groove metal band Pantera, with their chugging and rhytmic guitar riffs was a great influence to the NU genre.
The honor of establishing NU metal as a distinct genre, however, goes to Korn. Their self-titled innovative debut album from 1994 combined dark emotional spoken and aggressive vocals with staccato guitar riffs and funky rhythms. The album thus laid the framework for later bands of the genre.
The genre got more popular in the second half of the decade with successful and experimental bands like Deftones, Slipknot and Limp Bizkit. Limp Bizkit strangely enough became a symbol for both the genre's rise and fall. The first because of the huge success of the album "Significant Other" (1999), the latter because they were blamed for the violent actions at the Woodstock 1999 Festival.
NU metal got its peak at the turn of millenium with Linkin Park's debut album "Hybrid Theory" (2000). The band's sound was a lighter and more pop-oriented version of NU metal but the album was an enormous success selling about 30 million copies worldwide! Other bands like Papa Roach, Disturbed and P.O.D. also became very successful about the the same time.
NU metal lyrics were often angst-ridden or angry and in this regard they continued the tradition from grunge and alternative metal. The image and clothing was very expressive and a clear departure from the traditional metal style, with features such as like baggy pants, baseball caps, dreadlocks, spiky hair, bald heads, bleached or dyed hair and facial piercings.
New subgenres and waves of fashion tend to fade away when they get over exposed and commercialized. Just as with glam metal and grunge in the 90's, the popularity of NU metal waned in mid 2000 as album sales dropped and many NU metal bands changed style. However, much of the alternative and aggressive DNA of the genre was carried on by the big new thing in metal: metalcore. But at the same time, traditional metal was rising from the ashes, perhaps best symbolized by Bruce Dickinson's reunion with Iron Maiden.
On a side note: Parallell to NU metal's emergance as the new sound of metal, the ways of listening to music was changing as well. Downloading and sharing mp3-files was rapidly becoming the new way of listening to music. Streaming was not available though, so the CD was still alive. Check out this convienent CD-long streaming playlist for a useful introduction to the history of the NU metal genre: