ONCE, metal was the music of the outsider: The heavy thrashing guitars, roaring vocals and standard issue black leather jackets had about as much in common with the sweet world of pop as Ozzy Osbourne had with Aled Jones.

But no longer. Metal, like indie before it, has gone mainstream. As Korn, hailed by many as the forerunners of the nu-metal scene, prepare to play a gig at Manchester Arena on September 12, NICOLA MOSTYN looks at who's who in the nu-metal world, where it is going and asks, is it really so nu after all?

Korn

Who: Formed in the early 90s in Bakersfield, California, this hardcore rock quintet emerged with a sound soon to be dubbed nu-metal.

Story so far: The band released their eponymously titled debut album in 1994, blending hip hop with angry guitars and death metal in what was to be a very popular move. Korn's second album, released in 1998, was a commercial and critical success and in 1999 they followed it up with the multi platinum album Issues, just as nu-metal was beginning to lose its underground appeal.

However: Latest album, Untouchables, reveals a darker and mature side to the boys (who are, after all, in their thirties) meaning they have managed to keep their metal credibility. For now.

Linkin Park

Who: Formed in 1996, the band from Southern California were called Xero, before taking on lead singer Chester Bennington and changing the name to Hybrid Theory and then finally Linkin Park.

Story so far: The band were quick to make an impact on the Los Angeles club scene and soon bagged a contract from Warner Brothers Records. Their debut album in 2000, Hybrid Theory, fused metal, hip-hop, and pop and was followed in July this year by Reanimation, a CD of remixes.

However: Linkin Park are generally viewed as the Backstreet Boys of the nu-metal scene, a tag no self respecting rock outfit would be proud to call

their own. With their pre-teen audience and crowd pleasing anthemic songs, this is pretty much nu metal by numbers. If you own the T-Shirt, and you are over 10 years old, don't wear it in public.

Papa Roach

Who: Four high school friends from Northern California town of Vacaville, who formed Papa Roach in 1993, fronted by the ridiculously named Coby Dick.

Story so far: Papa Roach's first major label album was Infest, released in 2000, a rap rock fest which offered angst ridden songs about substance abuse, dysfunctional family life and suicide. So far so metal.

However: The band have moved away from their nu-metal tag, with a change in sound with latest album Lovehatetragedy, for which Coby returned to his original name, Jacoby Shaddix (no less ridiculous, some might say). Never fear, there is still plenty of angst to be had, with the hardships of touring serving as food for songs. Having also rejected the nu-metal tag with this return to simple rock, the band are likely to avoid the path taken by . . .

Limp Bizkit

Who: Rock/hip-hop oufit Limp Bizkit were formed in 1994 in Jacksonville, Florida, fronted by Fred Durst and containing House Of Pain member DJ Lethal.

Story so far: Limp Bizkit released their debut album Three Dollar Bill Y'All, in 1997, offering a hip-hop/metal crossover that was gratefully received by many. Alarmingly, the album contained a cover of George Michael's Faith. Second release, Significant Other, was also well-received and all boded well.

However: Limp Bizkit got involved in the reworking of the Mission Impossible theme, Take A Look Around, which brought them firmly into the mainstream and made them about as revolutionary as Starbucks. The 2000 album, Chocolate Starfish And The Hot Dog Flavored Water, was a slick, contagious commercial success but whispers of "sell out" were already beginning to circulate. As Fred Durst has proven, it's hard to rage against the Establishment once you are the Establishment. And when your fans are eight years old.

System Of A Down

Who: This California based alt-metal band began life as Soil and renamed themselves in 1995. Three of the members are of Armenian heritage and the band is fronted by Serj Tankian.

Story so far: The band built up a following on the southern California circuit and released their self titled debut album in June 1998, a fast paced mix of metal and beats. Their Eastern European influences and political inclinations means they have a more intelligent message to deliver than the usual metal mantra of 'Life Sucks'.

However: Second album, Toxicity, manages to live up to the first, and has raised the game for metal heads everywhere. With their dark songs, black humour and intelligent creations, System of a Down are set well apart from their peers, and prove that nu-metal isn't ready be bludgeoned out of shape by fashion just yet. It just needs to be made for the grown-ups.

Been There Done That

A look at the real daddies of the nu-metal sound

Red Hot Chili Peppers

These boys have been mixing hip hop and punk for years. Give It Away will never be bettered and they aren't too macho to break into a ballad every now and then with amazing results.

Rage Against The Machine

Fusing hip hop, metal and politics, this US four piece, fronted by the brilliantly aggressive Zack de la Rocha, came up with some storming tracks, including Killing In The Name, Bullet In The Head and Know Your Enemy. Nu-metal world take note.

Faith No More

The true godfathers of hard rock and an inspiration to every metal band out there.

If you love rock and you don't own Angel Dust, you should be ashamed of yourself.

Judgement Night

Back in 1993 rock and rap were mixing rap and metal quite nicely thank you, with this album which saw collaborations between the likes of Helmet and House Of Pain, Pearl Jam and Cyprus Hill. Well worth a listen.