Rap is a musical form of vocal delivery that incorporates “rhyme, rhythmic speech, and street vernacular”, which is performed or chanted in a variety of ways, usually over a backing beat or musical accompaniment. The components of rap include “content” (what is being said), “flow” (rhythm, rhyme), and “delivery” (cadence, tone). Rap differs from spoken-word poetry in that it is usually performed off time to musical accompaniment. Rap being a primary ingredient of hip hop music, it is commonly associated with that genre in particular; however, the origins of rap predate hip-hop culture by many years.
Precursors to modern rap include the West African griot tradition, certain vocal styles of blues, jazz, 1960s African-American poetry and Sprechgesang. The modern use of rap in popular music originated in the Bronx, New York City in the 1970s, alongside the hip hop genre and cultural movement. Rapping developed from the role of master of ceremonies (MC) at parties within the scene. They would encourage and entertain guests between DJ sets, which evolved into longer performances.
https://en.wikipedia.org/wiki/Rapping
