
Rap uses the spoken word as a rhythmic instrument. Rap DJs often use scratching and back spinning on vinyl discs to create the sound style for the vocalist to rap over.
Its roots are in the toasting of Jamaican DJs who spoke over rhythm and blues records, and in New York black street culture - where it went together with graffiti art,Hip-Hop and Break Dancing (so called because of the break-beats or short rhythmic phrases mixed together by 1970s DJs).

Public Enemy © Retna Pictures Ltd.
It was often a highly political style whose lyrics could include very controversial statements. Public Enemy rapped about black social issues, making political statements about black rights, racism and police brutality.
N.W.A. also rapped about contentious topics, and started Gangster Rap.
The music crossed over to a much larger - indeed world-wide - audience with the band Run-DMC whose records were a hit with white audiences as well as black.