King Crimson are a progressive rock band. Formed in London in 1968 (but featuring a transatlantic line-up since 1981), the band are widely recognised as a foundational progressive rock group (although the group members resist the label). The band have incorporated diverse influences and approaches during their five-decade history (including jazz and folk music, classical and experimental music, psychedelic rock, hard rock and heavy metal, new wave, gamelan, electronica and drum and bass) as well as balancing highly structured compositions against abstract improvisational sections and an interest in pop songs. The band has a large following, despite garnering little radio or music video airplay.
With guitarist Robert Fripp as the only consistent member (and therefore considered to be the band's leader and motive force), King Crimson's line-up has persistently altered throughout its existence. Eighteen musicians and three lyricists have passed through the ranks, although the tenure of certain members has sometimes extended for decades. King Crimson's sound has varied according to its instrumentation - earlier line-ups featured prominent saxophone and keyboards, while subsequent line-ups replaced this with (variously) violin, innovative acoustic or electronic percussion, interlocking guitars or touch-style instruments. The band are notable for continuous engagement with contemporary music technology - in addition to Fripp's extensive work in loop music both in and out of the band, King Crimson pioneered the use of Mellotrons in the 1960s; Roland guitar synthesizers, Simmons electronic drums and the Chapman Stick in the 1980s; dense MIDI processing and the Warr Guitar in the 1990s, and Roland V-Drums in the 21st century. King Crimson's existence has been characterised by regular periods of hiatus (each of which have been initiated and concluded by Fripp). From 1997 until the present day, various subdivisions of King Crimson have continued to pursue aspects of the band's work and approaches via a series of related bands collectively referred to as "ProjeKCts".
The debut line-up of King Crimson was influential but short-lived: lasting for just under one year, it established several of the ground rules of British progressive rock (a high standard of instrumental expertise, active technological engagement, complex multi-part compositions and the fusion of then-current psychedelic rock forms with classical, jazz and folk idioms). During 1970 and 1971 a second and unstable line-up struggled to unite disjunctions between increasingly formalised studio work and rougher live incarnations, going through numerous personnel changes while further exploring elements of jazz, funk and chamber music. Establishing a third, stable line-up in 1972, King Crimson developed a European-influenced improvisational sound with elements of hard rock, jazz fusion and a distinctly harsher classical component (mainly inspired by Béla Bartók) before breaking up in 1974. A fourth line-up of King Crimson was active between 1981 and 1984 - an Anglo/American quartet with new wave pop and gamelan influences. A fifth line-up (the 1980s quartet expanded to a six-piece) appeared in 1994, blending aspects of the band's 1980s and 1970s sound with fresh influences from genres such as industrial rock, grunge and loop music. Further line-ups of King Crimson have continued to work up until the present day, with the band continuing to incorporate new elements (such as drum and bass) into their music. The current line-up is a seven-piece band (Fripp, Jakko Jakszyk, Tony Levin, Mel Collins, Pat Mastelotto, Gavin Harrison and Bill Rieflin) with three drummers, a saxophonist/flautist, paired guitars, bass and assorted electronic devices. Due to the number of musicians involved in King Crimson over the years (plus the band's emphasis on creativity and on recruiting high-level players) the band is at the hub of a network of other bands and projects, and has been influential to many contemporary musical artists.