Rap

Rapping (also known as emceeing, MCing, spitting (bars), or just rhyming) refers to "spoken or chanted rhyming lyrics with a strong rhythmic accompaniment". The art form can be broken down into different components, as in the book How to Rap where it is separated into “content”, “flow” (rhythm and rhyme), and “delivery”. Rapping is distinct from spoken word poetry in that is it performed in time to the beat of the music.

Rapping is a primary ingredient in hip hop music, but the phenomenon predates hip hop culture by centuries. Rapping can be delivered over a beat or without accompaniment. Stylistically, rap occupies a gray area among speech, prose, poetry, and song. The use of the word to describe quick speech or repartee long predates the musical form, meaning originally "to hit". The word had been used in British English since the 16th century, and specifically meaning "to say" since the 18th. It was part of the African American dialect of English in the 1960s meaning "to converse", and very soon after that in its present usage as a term denoting the musical style. Today, the terms "rap" and "rapping" are so closely associated with hip hop music that many use the terms interchangeably. (For purposes of clarity, this article focuses on rapping as a technique or activity. For more information on the music genre, see hip hop music.)

Source : http://en.wikipedia.org/wiki/Rapping