Over 100 million albums and three decades since their formation at Dublin’s Mount Temple High School in 1978 – at the instigation of Larry Mullen who pinned an ad to the bulleting board – there’s little denying that U2 have cemented their reputation among the greatest rock acts in history. Moreover, by learning to roll with the punches over the years, together they have shared the memorable victories, and rare defeats, of an extraordinary career thus far. Remarkably, two decades on, they remain intact. No-one has ever left U2; no new member has ever joined.

In the tradition of the late ‘70s, U2 were a band before they could actually play, although all four members testify to the raw chemistry and unique spirit of the group being there from the outset. Burning with the intense energy of punk, the nascent U2 reacted against the burgeoning blank attitudes of their doomy, raincoat-wearing new wave contemporaries, emerging with wide-eyed hope.

Their first one-off Irish release, the U2-3 EP for CBS Records in 1979, was supported by a self-organised tour that left no-one doubting that U2 were driven men. Despite no offers of a major record deal following a round of London showcase gigs, the tour culminated in a sold-out show in front of two thousand fans in Dublin – a rare achievement for a band that, to all intents, remained unsigned. Further bolstering their reputation, in January 1980, the band topped five categories in the readers’ poll of Irish rock magazine Hot Press. In April of that year, U2 signed to Island Records releasing their first single, 11 O’Clock Tick Tock, the following month.

Over the next three years, U2 went from strength to strength, chiefly due to their relentless touring and blistering live performances which regularly found Bono going to often extraordinary lengths to capture the audience's imagination. Their first three Steve Lillywhite-produced albums - Boy (1980), October (1981) and War (their first UK No.1 in 1983) - defined a widescreen rock that clearly didn't have a roof over its head.

Furthermore, U2 were fast being regarded as the most politically motivated band since The Clash. At a Belfast show, before the first public airing of the provocative Sunday Bloody Sunday, Bono bluntly announced "If you don't like it, let us know..." What became clear was that U2 - on both political and emotional levels - were beginning to connect with a far wider audience worldwide. In the wake of 1983's Under A Blood Red Sky, a live document of the group's landmark performance at Colorado Red Rocks Amphitheatre, the writers of Rolling Stone magazine named U2 Band Of The Year.

Early in 1984, U2 made the surprising announcement that experimentalist Brian Eno (David Bowie, Talking Heads) and his protégé Daniel Lanois were to produce their fourth studio album. Recorded in the suitably cavernous ballroom of Slane Castle, near Dublin, The Unforgettable Fire offered a new, expansive, cinematic U2 sound as evidenced in Pride (In The Name Of Love), their biggest hit up to that point in both the UK and the States.

Their fifth album The Joshua Tree won the distinction of the fastest-selling UK album ever by going platinum within its first 48 hours on sale. The staggering success of the record - fuelled by hits With Or Without You, I Still Haven't Found What I'm Looking For and Where The Streets Have No Name - would far exceed even the band's own expectations, as it reached number 1 in twenty-two countries with worldwide sales of fifteen million copies. By 1987, awarded with Grammys for Album Of The Year and Best Rock Performance, U2 were quite simply the biggest rock band in the world.

By the end of the '80s, however, it seemed U2 had looked so deep into the past, they'd forgotten about their own future. At the close of their Lovetown tour of Australia, New Zealand and Japan, U2 performed four triumphant homecoming shows in Dublin. On the final night, New Year's Eve, 1989, Bono made a strong, symbolic hint that the band were on the verge of significant change.

At the close of that decade, few could have predicted the transformation that U2 would undergo with the dawning of the 1990s. Ready for the laughing gas, U2 travelled to Hansa Studios in Berlin and re-emerged in 1991 with Achtung Baby, before launching into the Zoo TV live experience. Widely lauded as the Sgt. Pepper of rock tours, it circumnavigated the globe twice in almost two years and the momentum propelled them through Zooropa - a planned single to be recorded in touring breaks that grew into an EP and eventually became their eighth album in 1993.

In 1997 came its successor, Pop, which topped the charts in 27 countries and gave them their second UK number one single in Discothèque. It was accompanied by the lemon scented sci-fi disco supermarket that was the PopMart world tour and which saw U2 fulfil their Zoo TV promise to bring their live show to the fledgling peace of Sarajevo.

Following Pop was All That you Can’t Leave Behind, which debuted in October of 2000 with the highly successful single Beautiful Day.

Then, in November of 2004, U2 released the politically charged How to Dismantle and Atomic Bomb. How to Dismantle an Atomic Bomb was regarded by Bono as their best record to datem but with the release of No Line on the Horizon, it would not be far fetched to say that this experimental album, which is unlike anything they have done before, will soon be hailed as their best work.