Pop music (a term that originally derives from an abbreviation of "popular") is a genre of popular music, which originated in its modern form in the Western world during the 1950s and 1960s, deriving from rock and roll. Unlike many earlier styles of popular music, rock lyrics have dealt with a wide range of themes in addition to romantic love: including sex, rebellion against "The Establishment", social concerns and life styles. These themes were inherited from a variety of sources, including the Tin Pan Alley pop tradition, folk music and rhythm and blues. Music journalist Robert Christgau characterizes rock lyrics as a "cool medium" with simple diction and repeated refrains, and asserts that rock's primary "function" "pertains to music, or, more generally, noise." The predominance of white, male and often middle class musicians in rock music has often been noted and rock has been seen as an appropriation of black musical forms for a young, white and largely male audience. As a result, it has been seen as articulating the concerns of this group in both style and lyrics. Similarly, 1970s punk culture spawned the visually distinctive goth and emo subcultures. New genres that emerged from this scene included progressive rock, which extended the artistic elements; glam rock, which highlighted showmanship and visual style; and the diverse and enduring subgenre of heavy metal, which emphasized volume, power, and speed. The sound of rock is traditionally centered on the electric guitar, which emerged in its modern form in the 1950s with the popularization of rock and roll, and was influenced by the sounds of electric blues guitarists. The sound of an electric guitar in rock music is typically supported by an electric bass guitar pioneered in jazz music in the same era, and percussion produced from a drum kit that combines drums and cymbals. This trio of instruments has often been complemented by the inclusion of others, particularly keyboards such as the piano, Hammond organ and synthesizers. The basic rock instrumentation was adapted from the basic blues band instrumentation (prominent lead guitar, second chord instrument, bass, and drums). A group of musicians performing rock music is termed a rock band or rock group and typically consists of between two and five members.
Rock music has also embodied and served as the vehicle for cultural and social movements, leading to major sub-cultures including mods and rockers in the UK and the hippie counterculture that spread out from San Francisco in the US in the 1960s. Further fusion subgenres have since emerged, including pop punk, rap rock, and rap metal, as well as conscious attempts to revisit rock's history, including the garage rock/post-punk and synthpop revivals at the beginning of the new millennium. Pop is not a do-it-yourself music but is professionally produced and packaged".
Typically, rock is song-based music usually with a 4/4 time signature using a verse-chorus form, but the genre has become extremely diverse. Like pop music, lyrics often stress romantic love but also address a wide variety of other themes that are frequently social or political in emphasis. Similarly, 1970s punk culture spawned the visually distinctive goth and emo subcultures. New genres that emerged from this scene included progressive rock, which extended the artistic elements; glam rock, which highlighted showmanship and visual style; and the diverse and enduring subgenre of heavy metal, which emphasized volume, power, and speed. From about 1967 the term was increasingly used in opposition to the term rock music, a division that gave generic significance to both terms. Whereas rock aspired to authenticity and an expansion of the possibilities of popular music, pop was more commercial, ephemeral and accessible. According to Simon Frith pop music is produced "as a matter of enterprise not art", is "designed to appeal to everyone" and "doesn't come from any particular place or mark off any particular taste". It has also made use of technological innovation. Punk was an influence into the 1980s on the subsequent development of other subgenres, including new wave, post-punk and eventually the alternative rock movement. Inheriting the folk tradition of the protest song, rock music has been associated with political activism as well as changes in social attitudes to race, sex and drug use, and is often seen as an expression of youth revolt against adult consumerism and conformity. Since the term rock began to be used in preference to rock and roll from the late-1960s, it has often been contrasted with pop music, with which it has shared many characteristics, but from which it is often distanced by an emphasis on musicianship, live performance and a focus on serious and progressive themes as part of an ideology of authenticity that is frequently combined with an awareness of the genre's history and development. According to Simon Frith "rock was something more than pop, something more than rock and roll.