Rapping (also dropping, rhyming, flowing, spitting, emceeing, or MCing) is an artistic form of vocal delivery and emotive expression that incorporates "rhyme, rhythmic speech, and [commonly] street vernacular". It is usually performed over a backing beat or musical accompaniment. The components of rap include "content" (what is being said, e.g., lyrics), "flow" (rhythm, rhyme), and "delivery" (cadence, tone). Rap differs from spoken-word poetry in that it is usually performed off-time to musical accompaniment. It also differs from singing, which varies in pitch and does not always include words. Because they do not rely on pitch inflection, some rap artists may play with timbre or other vocal qualities. Rap is a primary ingredient of hip-hop music, and so commonly associated with the genre that it is sometimes called "rap music".
Precursors to modern rap music include the West African griot tradition, certain vocal styles of blues and jazz, an African-American insult game called playing the dozens (see Battle rap and Diss), and 1960s African-American poetry. Stemming from the hip-hop cultural movement, rap music originated in the Bronx, New York City, in the early 1970s and became part of popular music later that decade. Rapping developed from the announcements made over the microphone at parties by DJs and MCs, evolving into more complex lyrical performances.