The band formed in 1976 when the members were teenagers with limited musical proficiency. By the mid-1980s, however, the band had become a top international act, noted for their anthemic sound, Bono's impassioned vocals, and The Edge's textural guitar playing. Their success as a live act was greater than their success at selling records until their 1987 album The Joshua Tree increased the band's stature "from heroes to superstars," according to Rolling Stone. U2 responded to the dance and alternative rock revolutions and their own sense of musical stagnation by reinventing themselves with their 1991 album Achtung Baby and the accompanying Zoo TV Tour. Similar experimentation continued for the rest of the 1990s. Since 2000, U2 pursued a more conventional rock sound that retains the influence of their previous musical explorations