Through a combination of zealous righteousness and post-punk experimentalism, U2 became one of the most popular rock & roll bands of the '80s. Equally known for their sweeping sound as for their grandiose statements about politics and religion, U2 were rock & roll
crusaders during an era of synthesized pop and heavy metal. 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 Adam Clayton and Larry Mullen Jr. played the songs as driving hard-rock, giving the band a forceful, powerful edge that was designed for arena rock. And their lead singer, Bono, was a frontman who had a knack of grand gestures that played better in arenas 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 superstars with the release of The Joshua Tree. Unlike many of their contemporaries, U2 was able to sustain their popularity in the '90s by reinventing themselves as a post-modern, 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.