Public Enemy, from New York City, personified a new sort of African-American music in the late 1980s. Rap, the competitive use of rhyming lines spoken over an ever-more-challenging rhythmic base, had a long history in African-American culture; however, it came to musical prominence as part of the hip-hop movement. Public Enemy used new digital technology to sample (use excerpts from other recordings) and recast the urban soundscape from the perspective of African-American youth. This was music that was at once sharply attuned to local political conditions and resonant internationally. By the mid-1990s rap had become an expressive medium for minority social groups around the world.

What does this version of rock's history--from Presley to Public Enemy--reveal? First, that rock is so broad a musical category that in practice people organize their tastes around more focused genre labels: the young Presley was a rockabilly, the Beatles a pop group, Dylan a folkie, Madonna a disco diva, Marley and the Wailers a reggae act, and Public Enemy rappers. Even Hendrix, the most straightforward rock star on this list, also has a place in the histories of rhythm and blues and jazz. In short, while all these musicians played a significant part in the development of rock, they did so by using different musical instruments and textures, different melodic and rhythmic principles, different approaches to song words and performing conventions.

Musical eclecticism and the use of technology

Even from a musicological point of view, any account of rock has to start with its eclecticism. Beginning with the mix of country and blues that comprised rock and roll (rock's first incarnation), rock has been essentially a hybrid form. African-American musics were at the centre of this mix, but rock resulted from what white musicians, with their own folk histories and pop conventions, did with African-American music--and with issues of race and race relations.

Rock's musical eclecticism reflects (and is reflected in) the geographic mobility of rock musicians, back and forth across the United States, over the Atlantic Ocean, and throughout Europe. Presley was unique as a rock star who did not move away from his roots; Hendrix was more typical in his restlessness. And if rock and roll had rural origins, the rock audience was from the start urban, an anonymous crowd seeking an idealized sense of community and sociability in dance halls and clubs, on radio stations, and in headphones. Rock's central appeal as a popular music has been its ability to provide globally an intense experience of belonging, whether to a local scene or a subculture. Rock history can thus be organized around both the sound of cities (Philadelphia and Detroit, New York City and San Francisco, Liverpool and Manchester) and the spread of youth cults (rock and roll, heavy metal, punk, and grunge).

Rock is better defined, then, by its eclecticism than by reference to some musical essence, and it is better understood in terms of its general use of technology rather than by its use of particular instruments (such as the guitar). Early rock-and-roll stars such as Presley and Buddy Holly depended for their sound on engineers' trickery in the recording studio as much as they did on their own vocal skills, and the guitar became the central rock instrument because of its amplified rather than acoustic qualities. Rock's history is tied up with technological shifts in the storage, retrieval, and transmission of sounds: multitrack tape recording made possible an experimental composition process that turned the recording studio into an artist's studio; digital recording made possible a manipulation of sound that shifted the boundaries between music and noise. Rock musicians pushed against the technical limits of sound amplification and inspired the development of new electronic instruments, such as the drum machine. Even relatively primitive technologies, such as the double-deck turntable, were tools for new sorts of music making in the hands of the "scratch" deejay, and one way rock marked itself off from other popular musical forms was in its constant pursuit of new sounds and new sound devices.

Rock and youth culture

This pursuit of the new can be linked to rock's central sociological characteristic, its association with youth. In the 1950s and early 1960s this was a simple market equation: rock and roll was played by young musicians for young audiences and addressed young people's interests (quick sex and puppy love). It was therefore dismissed by many in the music industry as a passing novelty, "bubblegum," akin to the yo-yo or the hula hoop. But by the mid-1960s youth had become an ideological category that referred to a particular kind of hedonism, individualism, and modernism. Whereas youth once referred to high-school students, it came to include college students. Moreover, rock became multifunctional--dance and party music on the one hand, a matter of serious attention and intimate expression on the other. As