During the second World War, the United States military used a shibboleth - a word or phrase that can be used to distinguish members of a group from outsiders - to prevent infiltration of their ranks by Japanese spies. The shibboleth they used was "lollapalooza", which was difficult for even the most proficient English-speaking Japanese spy to pronounce.

Shibboleths need not always be verbal; you can have a shibboleth through action. During the war, the Nazis had a test to root out unidentified Jews in a particular grouping. They would serve tea to the group and place sugar cubes on the table. The Jewish people would place the sugar cube in their mouths, while the ethnic Germans would place it in their tea.

Perry Farrell of Jane's Addiction uses the shibboleth lollapalooza for the name of his touring alt.rock festival that has now been running (with a few fallow years) since 1991. Lollapalooza has always been different, and not just because it's programmed by an actual musician as opposed to a businessman promoter. Unlike Woodstock, which was a one-off, the festival is an annual event. And, unlike Glastonbury, which you travel to, the festival travels to its audience by taking in a number of centres during its run.

Farrell is always intent on keeping things very "alt". There are non-musical features (The Jim Rose Circus, the Shoaling Monks etc), art exhibitions, virtual reality games and political/environmental information booths.

Lollapalooza peaked in the early '90s as a must-do Generation X event. What really propelled it away from the alt ghetto, though, was the concomitant explosion in alt.rock, notably grunge. But there's no failure like success, and Farrell soon found that his alt festival had inadvertently become a mainstream event.

If the original idea was to programme bands who weren't getting radio/MTV/national press exposure, he soon found that his headliners were making the cover of Time magazine. In 1991, for example, the main acts were Siouxsie and the Banshees, Ice T and Butthole Surfers. By 1994 they were Smashing Pumpkins, Green Day and the Beastie Boys.

What really did it for Lollapalooza, though, was the highly controversial decision to put Metallica on the Main Stage in 1996.

This was years before Metallica shamed themselves in their reaction to Napster and had everything to do with the fact that an avowedly "non-mainstream" festival (something which they made a great deal out of) was signing up a mainstream festival act. And don't kid yourself about Metallica: They may dress in black clothes and play loud guitars, but in festival currency they're no different from The Eagles.

Two years later, Lollapalooza was as dead as the Monty Python parrot.

Over the last three years, the festival tentatively returned in a slimmed-down format, and now this year it's back and bigger than ever before. Judging by the line-up, it's not that Farrell has given up on the alt idea altogether, it's just that the old music industry shibboleths about alt and mainstream have simply become redundant, and, more importantly, are of no concern whatsoever to today's festival-goers.

Lollapalooza is no longer a "bizarre bazaar" of music, art and politics. Whatever countercultural impulses it once had have atrophied.

Perhaps the biggest change is that the festival no longer travels. It is now a three-day event in Chicago in early August. Farrell removed the touring because he didn't want to "collaborate" with the giant US promoters who now run everything (and most everybody). It's simply a sad acknowledgement of modern-day music promotion economics.

He still managed to get 130 musical acts to play over nine stages and did a mighty job in avoiding all the usual festival names to come up with a very appealing line-up: Kanye West, Queens of the Stone Age, Death Cab for Cutie, The Raconteurs, Gnarls Barkley, Common, The Flaming Lips, Wilco and Broken Social Scene.

And the more sedate type of older Generation X festivalgoer wasn't forgotten: three-day passes were $150, but for $600 you could get a spot on an elevated seating platform, food and beverages, massages and a facial.