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. Rock music is a genre of popular music that originated as "rock and roll" in the United States in the 1950s, and developed into a range of different styles in the 1960s and later, particularly in the United Kingdom and the United States. It has its roots in 1940s' and 1950s' rock and roll, itself heavily influenced by blues, rhythm and blues and country music. The term "pop song" is first recorded as being used in 1926, in the sense of a piece of music "having popular appeal". Hatch and Millward indicate that many events in the history of recording in the 1920s can be seen as the birth of the modern pop music industry, including in country, blues and hillbilly music. 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. 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.
Pop is not a do-it-yourself music but is professionally produced and packaged". Throughout its development, pop music has absorbed influences from most other genres of popular music. 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.
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. since the late 1950s, however, pop has had the special meaning of non-classical mus[ic], usually in the form of songs, performed by such artists as the Beatles, the Rolling Stones, ABBA, etc". Grove Music Online also states that "… 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". 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. Harmonies range from the common triad to parallel fourths and fifths and dissonant harmonic progressions. Rock songs, since the late 1950s and particularly from the mid-1960s onwards, often used the verse-chorus structure derived from blues and folk music, but there has been considerable variation from this model. Critics have stressed the eclecticism and stylistic diversity of rock. Because of its complex history and tendency to borrow from other musical and cultural forms, it has been argued that "it is impossible to bind rock music to a rigidly delineated musical definition. It has also made use of technological innovation. 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). 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. From the 1990s alternative rock began to dominate rock music and break through into the mainstream in the form of grunge, Britpop, and indie rock.