Both rap and rock music were created by African-American musicians as a means of highlighting their struggle to be accepted in America. The music of Chuck Berry, often referred to as "The Father of Rock & Roll," struck a chord with both white and black audiences. Rap music has similarly moved outside of the African-American communities where it was first created, and has evolved into a successful, widely accepted mainstream music genre.
Two decades ago, almost all rap music was made by pairing sampled music with drum machines such as the Roland TR-808 and 909. Today, it is just as common for a hip hop group to record and perform with a live band as it is for a rock band to incorporate DJs, samples and drum machines into performances. Artists such as Kanye West and the Beastie Boys blur the line between rock and rap star.
Drums and bass form the backbone for a high percentage of the hit songs produced by either genre. The combination of bass and drum rhythms dictate the momentum of the song, whether propelling forward at a hurried pace or settling into a slow, easy groove. A good rhythm section is widely regarded as a critical element to success in both rock and rap. It is common for a hip-hop song be composed of nothing but a repeating four-bar drum beat and a simple bass line. Rock music is similarly simplistic, while adding guitars to the mix.
It is common for rap and rock musicians to collaborate on projects, further blurring the line between the genres. Some of the more famous rock/rap collaborations are "Bring the Noise" by Anthrax and Public Enemy, "Iron Man (This Is War)" by Busta Rhymes featuring Ozzy Osbourne, and "Radio Song" by REM and KRS One. In 2004, Jay-Z and Linkin Park collaborated on an entire live performance, which was released in the form of an EP. Today, bands such as Linkin Park, Limp Bizkit and Rage Against The Machine are identified as "Rock/Rap" artists.