The terms "popular music" and "pop music" are often used interchangeably, although the former is a description of music which is popular (and can include any style). It is "not driven by any significant ambition except profit and commercial reward … Such elements include generally short to medium-length songs, written in a basic format (often the verse-chorus structure), as well as the common employment of repeated choruses, melodic tunes, and hooks. 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. 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".
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. Early pop music drew on the sentimental ballad for its form, gained its use of vocal harmonies from gospel and soul music, instrumentation from jazz, country, and rock music, orchestration from classical music, tempo from dance music, backing from electronic music, rhythmic elements from hip-hop music, and has recently appropriated spoken passages from rap. The terms "popular music" and "pop music" are often used interchangeably, although the former is a description of music which is popular (and can include any style).
Rock places a higher degree of emphasis on musicianship, live performance, and an ideology of authenticity than pop music. According to Grove Music Online, "Western-derived pop styles, whether coexisting with or marginalizing distinctively local genres, have spread throughout the world and have come to constitute stylistic common denominators in global commercial music cultures". Some non-Western countries, such as Japan, have developed a thriving pop music industry, most of which is devoted to Western-style pop, has for several years has produced a greater quantity of music of everywhere except the USA. The spread of Western-style pop music has been interpreted variously as representing processes of Americanization, homogenization, modernization, creative appropriation, cultural imperialism, and/or a more general process of globalization. Rock musicians combined an emphasis on skill and technique with the romantic concept of art as artistic expression, original and sincere". In the new millennium the term rock has sometimes been used as a blanket term including forms such as pop music, reggae music, soul music, and even hip hop, with which it has been influenced but often contrasted through much of its history.. 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. The terms "popular music" and "pop music" are often used interchangeably, although the former is a description of music which is popular (and can include any style). 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. By the late 1960s, referred to as the "golden age" or "classic rock" period, a number of distinct rock music subgenres had emerged, including hybrids like blues rock, folk rock, country rock, raga rock, and jazz-rock fusion, many of which contributed to the development of psychedelic rock, which was influenced by the countercultural psychedelic scene. 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. 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.