THE rock annals are so full of myth and invention that every now and again when the real deal shows up, it takes a while to recognize it for what it is.

Noel Gallagher's memories of his first appearance at the UK's biggest rock festival, Glastonbury, in 1994 are episodic and intimate, like outtakes from a movie he'd wandered into. They're of things like taking possession of a backstage caravan from the band he'd once worked for as a roadie, and coming offstage to be told that Oasis's second UK single, "Shakermaker," had climbed to number eleven in the UK chart; of someone from their record label Creation Records being disappointed to fall short of the top ten while the band, having just heard their music soaring towards a horizon for the first time, now knew there would be no space they couldn't fill, were individually thrilled. Noel recalls having the astonishing intimation that the band's dreams were about to become true. Oasis were at the forefront of a new generation of British guitar groups who stepped out of the shadow of native dance culture and American grunge, with eyes fixed on the mainstream in a way that would have been unthinkable a few years before. 60,000 people went away from that first Glastonbury performance and told a million others about the thrill of what they'd seen: about this band who were the absolute primal essence of rock and roll, refined and distilled to ragged perfection - the impact of whose music, then as now, was so bafflingly much greater than the sum of its parts. We all went away knowing we'd seen something great and that the acts who followed Oasis that afternoon might as well not have bothered.

Talk to the Gallagher brothers about how they made it that far and you get no romanticisation, because while their tale might read like a fairy story now, that's not how it began, and you don't have to delve far to find echoes of rock's origins in the Delta. The details of their early lives in the tough Manchester, UK district of Burnage are well documented, but fortunately there were compensations in the form of an old guitar their father brought home one day - in which Noel found refuge for hours at a time - and regular trips to the local Maine Road Stadium to watch Manchester City play football. In the case of the latter, what fascinated the boys was not so much the action on the pitch, but the ‘stands full of crowds singing together, something you never saw (and still seldom see) anywhere else. And what they sang was so uplifting. Noel had been born three days before the release of The Beatles' Sergeant Pepper, but football provided his first real experience of music and it may be coincidence that songs like "Don't Look Back in Anger" and "Champagne Supernova" seem to come fully alive in a stadium; that Oasis are one of the few bands you'd rather see in that environment than in a sweaty club. But there again, it may not. Critics who dismiss Oasis's songs as populist fail to recognize the core emotion behind them, which is yearning.

So in their different ways, the songs are mostly about transcendence and it's arguable that what we have here is a form of English soul music... which also explains the uniquely intimate relationship between Oasis and their fans - why their audience not only remains constant, but constantly renews itself, regardless of whatever vogues are playing elsewhere.

Liam formed the band. Noel never played in one until he came home from roadying for Inspiral Carpets and managed to persuade the four friends from the original lineup that he should join forces with them. Liam appears to have been born to his destiny as a rock star - his mother tells a story of him covering dropped lines in a nativity play with a spontaneous impression of Elvis - but Noel expected to be a builder like his dad. None of his mates were into music, but a first sighting of local boys The Smiths in 1984 turned his world upside down, with Liam equally besotted by The Stone Roses' legendary early Manchester shows, setting the seal on the brothers' musical ambitions a few years later.

We often assume the rise of Oasis to have been instant and unchallenged, but it wasn't: the first review in Britain's NME was noncommittal and the second scathing. Nevertheless, by the time that blistering debut album Definitely Maybe arrived, most observers had no trouble recognising it as a stone cold classic. The instinctive theme was the band's dream of escaping the life they'd been born to, but where a song like Rock ‘n' Roll Star, with its chorus of ‘Tonight...I'm a rock ‘n' roll star!' could seem aloof in other hands, this song wasn't about being a rock star, it was about feeling like one; about that fleeting sense of immortality you got when you stalked into a bar knowing you looked great, felt great, were the very essence and summation of being - the sense that existence could never, ever have more to offer than this. No one has ever captured this precarious thrill better than Noel, while Liam seems its perpetual embodiment. The singer's six-syllable phrasing of the word ‘imagination' in the first line of "Cigarettes & Alcohol" makes it easily the most iconic song line of the 1990s.

Everything which followed was built on this ecstatic foundation. The second album, (What's The Story) Morning Glory?, went over the top when "Wonderwall" became a world-wide anthem of 1995. Then there was the insanity surrounding the release of the band's third album, Be Here Now, in 1997, of a type not visited upon the British Isles since Beatlemania and which no album could hope to live up to. Notwithstanding its author's retrospective belief that Be Here Now was rushed, it springs a lot of surprises when listened to with fresh ears at this remove: at the very least, it looks like the most perfect expression of its time, which seemed to feed the inevitable post-millennial comedown, and a sense of disorientation which found focus in Standing on the Shoulder of Giants, the album made just before the sudden departure of founder members Bonehead and Guigs. All the same, a period of rebuilding both band and the brothers' personal lives culminated in 2002's Heathen Chemistry, which combined the band's best collection of songs since Morning Glory with the fresh drive provided by new members Gem Archer and Andy Bell.

The interesting thing about the story so far is that, throughout, the group's live audience continued to grow on a world-wide scale, perhaps because the brothers' triumphs and travails seemed to reflect our own as individuals. Just as they are a part of our story, we feel ourselves to be a part of theirs and perhaps the most revealing thing Noel Gallagher has ever said about the band came in response to a question concerning their lack of razzmatazz live, to which he replied simply that "if you take the emphasis away from razzmatazz, the audience gets more involved with itself." And now we seem to have entered a second phase. Their most recent album, Don't Believe The Truth, rightly heralded as a triumphant return, differs from its predecessors in that the writing is shared amongst the band. Liam continues to blossom and mature as a songwriter, while Gem Archer and Andy Bell have stepped forward with telling contributions and are making it increasingly hard to remember a time when they weren't around. Meanwhile, Noel's own tunes seem to be engaging with the world in a more direct way, almost as wry Information Age protest songs in some cases. Where this might lead, it's impossible to know, but anyone who saw 2005/06's world tour will have found Oasis looking and sounding as vital as at any time since '94.