Progressive rock, also known as prog rock or prog, is a rock music subgenre that originated in the United Kingdom, with further developments in Germany, Italy, and France, throughout the mid-to-late 1960s and 1970s. It developed from psychedelic rock and originated, similarly to art rock, as an attempt to give greater artistic weight and credibility to rock music. Bands abandoned the short pop single in favor of instrumentation and compositional techniques more frequently associated with jazz or classical music in an effort to give rock music the same level of musical sophistication and critical respect. Songs were replaced by musical suites that often stretched to 20 or 40 minutes in length and contained symphonic influences, extended musical themes, fantasy-like ambiance and lyrics, and complex orchestrations. Music critics, who often labeled the concepts as "pretentious" and the sounds as "pompous" and "overblown," tended to be hostile toward the genre or to completely ignore it.
Progressive rock saw a high level of popularity throughout the 1970s, especially in the middle of the decade. Bands such as Jethro Tull, The Moody Blues, Pink Floyd, Yes, King Crimson, Genesis, and Emerson, Lake & Palmer (ELP) were the genre's most influential groups and were among the most popular acts of the era, although there were many other, often highly influential, bands who experienced a lesser degree of commercial success. The genre faded in popularity during the second half of the decade. Conventional wisdom holds that the rise of punk rockcaused this, although in reality a number of factors contributed to this decline. Progressive rock bands achieved commercial success well into the 1980s, albeit with changed lineups and more compact song structures.
The genre grew out of the 1960s space rock of Pink Floyd and the classical rock experiments of bands like The Moody Blues, Procol Harumand The Nice. Most of the prominent bands from the genre's 1970s heyday fall into the "symphonic prog" category, in which classical orchestrations and compositional techniques are melded with rock music. Other subgenres exist, including the more accessible neo-progressive rock of the 1980s, the jazz-influenced Canterbury sound of the 1960s and 1970s, and the more political and experimental Rock in Opposition movement of the late 1970s and onward. Progressive rock has influenced genres such as krautrock and post-punk, and it has fused with other forms of rock music to create such sub-genres as neo-classical metal and progressive metal. A revival, often known as new prog, occurred at the turn of the 21st century and has since enjoyed a cult following.