Through a combination of zealous righteousness and post-punk experimentalism, U2 became one of the most popular rock & roll bands of the '80s. They were rock & roll crusaders during an era of synthesized pop and heavy metal, equally known for their sweeping sound as for their grandiose statements about politics and religion. The Edge provided the group with a signature sound by creating sweeping sonic landscapes with his heavily processed, echoed guitars. Though the Edge's style wasn't conventional, the rhythm section of Larry Mullen, Jr. and Adam Clayton played the songs as driving hard rock, giving the band a forceful, powerful edge that was designed for arenas. And their lead singer, Bono, was a frontman with a knack of grand gestures that played better in stadiums than small clubs. It's no accident that footage of Bono parading with a white flag with "Sunday Bloody Sunday" blaring in the background became the defining moment of U2's early career -- there rarely was a band that believed so deeply in rock's potential for revolution as U2, and there rarely was a band that didn't care if they appeared foolish in the process.

During the course of the early '80s, the group quickly built up a dedicated following through constant touring and a string of acclaimed records. By 1987, the band's following had grown large enough to propel them to the level of international superstardom with the release of The Joshua Tree. Unlike many of their contemporaries, U2 were able to sustain such popularity in the '90s by reinventing themselves as a postmodern, self-consciously ironic, dance-inflected pop/rock act, owing equally to the experimentalism of late-'70s Bowie and '90s electronic dance and techno. By performing such a successful reinvention, the band confirmed its status as one of the most popular bands in rock history, in addition to earning additional critical respect.

With its textured guitars, U2's sound was undeniably indebted to post-punk, so it's slightly ironic that the band formed in 1976, before punk had even reached their hometown of Dublin, Ireland. Larry Mullen, Jr. (born October 31, 1961; drums), posted a notice on a high-school bulletin board asking for fellow musicians to form a band. Bono (born Paul Hewson, May 10, 1960; vocals), the Edge (born David Evans, August 8, 1961; guitar, keyboards, vocals), Adam Clayton (born March 13, 1960; bass), and Dick Evans responded to the ad, and the teenagers banded together as Beatles and Stones cover band called the Feedback. They then changed their name to the Hype in 1977. Shortly afterward, Dick Evans left the band to form the Virgin Prunes, and the group changed names once again, this time adopting the moniker of U2.

U2's first big break arrived in 1978, during the members' final year of high school, when they won a talent contest sponsored by Guinness. By the end of the year, the Stranglers' manager, Paul McGuinness, had seen the band play and offered to manage them. Even with a powerful manager in their corner, the band had trouble making much headway, and they failed an audition with CBS Records at the end of the year. In the fall of 1979, U2 released their debut EP, U2 Three. The EP was available only in Ireland, where it topped the national charts. Shortly afterward, they began to play in England, but they failed to gain much attention away from home.

U2 scored one more chart-topping single, "Another Day," in early 1980 before Island Records offered the group a contract. Later that year, the band's full-length debut, Boy, was released. Produced by Steve Lillywhite, the record's sweeping, atmospheric but edgy sound was unlike most of its post-punk contemporaries, and the band earned further attention for its public embrace of Christianity; only Clayton was not a practicing Christian. Through constant touring, including opening gigs for Talking Heads, U2 was able to take Boy into the American Top 70 in early 1981. October, also produced by Lillywhite, followed in the fall, and it became their British breakthrough, reaching number 11 on the charts. By early 1983, Boy's "I Will Follow" and October's "Gloria" had become staples on MTV, which, along with their touring, gave the group a formidable cult following in the U.S.

Released in the spring of 1983, the Lillywhite-produced War became U2's breakthrough release, entering the U.K. charts at number one and elevating them into arenas in the United States, where the album peaked at number 12. War had a stronger political message than its predecessors, as evidenced by the international hits "Sunday Bloody Sunday" and "New Year's Day." During the supporting tour, the band filmed its concert at Colorado's Red Rocks Amphitheater, releasing the show as an EP and video titled Under a Blood Red Sky. The EP entered in the U.K. charts at number two, becoming the most successful live recording in British history. U2 had become one of the most popular bands in the world, and their righteous political stance soon became replicated by many other bands, providing the impetus for the Band Aid and Live Aid projects in 1984 and 1985, respectively.

For the follow-up to War, U2 entered the studios with co-producers Brian Eno and Daniel Lanois, who helped give the resulting album an experimental, atmospheric tone. Released in the fall of 1984, The Unforgettable Fire replicated the chart status of War, entering the U.K. charts at number one and reaching number 12 in the U.S. The album also generated the group's first Top 40 hit in America with "(Pride) In the Name of Love," a tribute to Martin Luther King, Jr. U2 supported the album with a successful international tour, highlighted by a show-stealing performance at Live Aid. Following the tour, the band released the live EP Wide Awake in America in 1985.

While U2 had become one of the most successful rock bands of the '80s, they didn't truly become superstars until the spring 1987 release of The Joshua Tree. Greeted with enthusiastic reviews, many of which proclaimed the album a masterpiece, The Joshua Tree became the band's first American number one hit and their third straight album to enter the U.K. charts at number one; in England, it set a record by going platinum within 28 hours. Generating the U.S. number one hits "With or Without You" and "I Still Haven't Found What I'm Looking For," The Joshua Tree and the group's supporting tour became the biggest success story of 1987, earning U2 the cover of respected publications like Time magazine. U2 decided to film a documentary about their American tour, recording new material along the way. The project became Rattle & Hum, a film that was supported by a double-album soundtrack that was divided between live tracks and new material. While the album Rattle & Hum was a hit, the record and film received the weakest reviews of U2's career, with many critics taking issue with the group's fascination with American roots music like blues, soul, country, and folk. Following the release of Rattle & Hum, the band took an extended hiatus.

U2 reconvened in Berlin in 1990 to record a new album with Eno and Lanois. While the sessions for the album were difficult, the resulting record, Achtung Baby, represented a successful reinvention of the band's trademark sound. Where they had been inspired by post-punk in the early career and American music during their mid-career, U2 delved into electronic and dance music with Achtung Baby. Inspired equally by late-'70s Bowie and the Madchester scene in the U.K., Achtung Baby was sonically more eclectic and adventurous than U2's earlier work, and it didn't alienate their core audience. The album debuted at number one throughout the world and spawned Top Ten hits with "Mysterious Ways" and "One."

Early in 1992, the group launched an elaborate tour to support Achtung Baby. Dubbed Zoo TV, the tour was an innovative blend of multimedia electronics, featuring a stage filled with televisions, suspended cars, and cellular phones. Bono devised an alter ego called the Fly, which was a knowing send-up of rock stardom. Even under the ironic guise of the Fly and Zoo TV, it was evident that U2 were looser and more fun than ever before, even though they had not abandoned their trademark righteous political anger. Following the completion of the American Zoo TV tour in late 1992 and preceding the launch of the tour's European leg, U2 entered the studio to complete an EP of new material that soon became the full-length Zooropa. Released in the summer of 1993 to coincide with the tour of the same name, Zooropa demonstrated a heavier techno and dance influence than Achtung Baby and received strong reviews. Nevertheless, the album stalled at sales of two million and failed to generate a big hit single. During the subsequent Zooropa tour, the Fly metamorphosed into the demonic MacPhisto, which dominated the remainder of the tour. Upon the completion of the Zooropa tour in late 1993, the band took another extended break.

During 1995, U2 re-emerged with "Hold Me, Thrill Me, Kiss Me, Kill Me," a glam rock theme to Batman Forever that was produced by Nellee Hooper (Björk, Soul II Soul). Later that year, they recorded the collaborative album Original Soundtracks, Vol. 1 with Brian Eno, releasing the record under the name the Passengers late in 1995. It was greeted with a muted reception, both critically and commercially. Many hardcore U2 fans (including drummer Larry Mullen, Jr.) were unhappy with the Passengers project, and U2 promised their next album, to be released in the fall of 1996, would be a rock & roll record.

The album took longer to complete than usual, ultimately being pushed back to the spring of 1997. During its delay, a few tracks, including the forthcoming first single "Discotheque," were leaked, and it became clear that the new album was going to be heavily influenced by techno, dance, and electronic music. When it was finally released, Pop did indeed bear a heavier dance influence, but it was greeted with strong initial sales and a few positive reviews. Demand for the album lessened in the following months, however, and Pop ultimately became the band's least popular album in over a decade. In late 1998, the group returned with Best of 1980-1990, the first in a series of hits collections issued in conjunction with a reported 50 million dollar agreement with Polygram. Included in the comprehensive track list was a remixed version of "Sweetest Thing," originally released as B-side in 1987, which charted well in multiple countries.

Three years after the mediocre response to Pop, U2 teamed up with Eno and Lanois once again to release All That You Can't Leave Behind in fall 2000. The album was heralded as a return to form, melding the band's classic sound with contemporary trends. It topped charts around the world, reached number three in America, earned Grammy Awards for the singles "Beautiful Day" and "Walk On," and became the band's biggest-selling record in years. (The Elevation tour that followed also brought U2 a hefty paycheck.) Steve Lillywhite, producer of the early-'80s landmarks Boy, October, and War, returned to the helm for U2's next record, How to Dismantle an Atomic Bomb. Released in November 2004, it hit the top of the Billboard charts and quickly gained platinum status. The album also garnered eight Grammy Awards, including Album of the Year, Rock Album of the Year, and Song of the Year (for "Sometimes You Can't Make It on Your Own," which Bono had written for his father). U2 were inducted into the Rock & Roll Hall of Fame in early 2005 and launched an international tour soon after, selling out arena venues in the U.S. and outdoor stadium shows abroad. The Vertigo Tour became the highest-grossing tour of 2005; by the time the entire tour concluded in late 2006, its gross of $389 million had made it the second most successful tour ever.

U2 returned to the drawing board in 2006 by partnering with veteran rock producer Rick Rubin. Two songs from those sessions appeared on the compilation U218 Singles, but the remaining material was ultimately scrapped. The band then turned to longtime friends Brian Eno, Daniel Lanois, and Steve Lillywhite, all of whom helped shape the sound of U2's 12th studio effort. Entitled No Line on the Horizon, the album was originally slated to appear in October 2008, although the release date was ultimately pushed back to March 2009. No Line on the Horizon was met with enthusiastic reviews but failed to yield a big radio single; even so, the band embarked on another lucrative tour that summer, with a second leg planned for 2010.

Source : http://allmusic.com