Before 1991, when and if it was used, the term "lollapalooza" was merely a way to describe something that was really, really awesome. Then Jane's Addiction frontman and modern shaman Perry Farrell wrapped his spindly arms around the anachronistic term and molded it into the modern definition of an American music festival.

When the gates open Friday (August 5) on this year's edition of Lollapalooza, all the names and faces will be different from that first touring edition of the granddaddy of American festivals, but one thing will remain unchanged: the music.

Asked if he ever imagined Lolla would still be around 20 years down the line (the first touring edition ran from 1991 to 2003 before being reborn as a destination event in Chicago in 2005), co-founder and Lolla partner Marc Geiger said, well, yes. "Someone pulled a quote from 1995 with me where I said, 'We're doing this now so we can still be around in 2010,' " said the legendary music agent, who was one of the first ones to buy into Farrell's vision of a traveling carnival that brought together music, sideshow acts, art and socially conscious vendors while melding rap, rock, punk and every other kind of music under the sun.

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And while music has fractured into a million different micro-genres since the days when bands as diverse as the Smashing Pumpkins, Nine Inch Nails, Cypress Hill, Metallica, Cheap Trick and Snoop Dogg could each find a home at Lolla, in some ways, Geiger said it's even simpler today than it was back when the "alternative" music fanbase was much smaller.

"It's easier when you're dealing with more numbers. With 130 bands, you can hit more genres in general, whether it's folk or techno house, there's just a bunch of room under the heading of 'good music,' " he said. "One year, we did Metallica and also had the Cocteau Twins ... and now you have Coldplay vs. deadmau5."

That concept is borne out by this year's mashed-up roster, which over the course of three days (Friday through Sunday) will range from such [article id="1662653"]headliners as Muse, Coldplay, Foo Fighters, Eminem[/article], Cee Lo Green and My Morning Jacket to dance acts Afrojack, Modeselektor, Skrillex and Glitch Mob, as well as indie acts such as the Mountain Goats and Best Coast. VMA-nominated bands Cage the Elephant and Foster the People are also in the mix, along with [article id="1668395"]VMA performers Young the Giant[/article].

Former Fall Out Boy bassist Pete Wentz was only 12 years old when the original festival launched, but ever since it put down roots in his childhood hometown, he's been a regular. And this year's event is even more special, since he'll be performing at Lolla for the first time ever with his new band, the [article id="1660076"]electro-pop combo Black Cards[/article]. "I remember hearing about it as a kid and wondering, 'What is this thing with all these crazy bands on it?,' " Wentz told MTV News. "They had really taken the European model and changed it and made it this touring thing."

Like so many over the years, Wentz could vividly recall transcendent musical moments he's had at Lollapalooza, which unfolds in the city's scenic Grant Park over a huge expanse of green space that gives it one of the most unique urban music-festival settings in the world. "I remember watching Girl Talk [in 2008] on one of the small stages, and it was absolutely bonkers," he said of the mash-up DJ's now-legendary set at that year's event. The bassist also remembered how, after that Girl Talk set, he was tired and ragged when, while walking past the golf-cart path outside the fence, Farrell himself barreled by. "He stopped the cart and told us to get on the back. He said, 'You guys look beat. Get in.' That was a pretty rad thing for him to do."

Wentz also mused about the 2007 headlining set by techno masters Daft Punk, which he said was probably one of the most insane outdoor concert experiences he's ever had. "I was standing out in the crowd when the pyramid lit up, and I was thinking, 'This would be the perfect time for somebody to do hallucinogenic drugs,' " he said. "But I don't do them."

Geiger thinks that 20 years in Lollapalooza has become a kind of musical rite of passage for each new generation. "Everything has changed [since we started]," he said, noting that the event now draws more than 285,000 over three days with a massive lineup that he likens to a kind of scavenger hunt. "The difference between Lollapalooza and other festivals is that you have the food, the aftershows at clubs, the lakefront site ... it's not like going to the Southside of Chicago for a festival for eight hours. You are there for two to three days and there's more friends, more leisure time and more planning on where you want to go and what you want to see."

As for what sets it apart from similarly sprawling fests like Coachella or Bonnaroo, Geiger laughed: "Location, location, location."

MTV News is in Chicago for Lollapalooza 2011! Stick with us all weekend as we cover the bands you love and the bands you will love soon.