Rapping is one of the elements of hip hop and the distinguishing feature of hip hop music ; it is a form of rhyming lyrics spoken rhythmically over musical instruments, with a musical backdrop of sampling, scratching and mixing by DJs. Originally, rapping was called MCing and accompanied DJing.

Origins :
Rapping (as a self-conscious artistic school) began as a variation on the toasting found in reggae, funk and dub music, mixed with influences from jazz-related performance poetry (Langston Hughes’s album Weary Blues being an important example ; the Beats also notable), radio DJ patter, and the tradition of playing the dozens. Among other influences and predecessors were talking blues records and such variations as Bob Dylan’s Subterranean Homesick Blues ; much of the work of James Brown and Parliament was also influential. The original rappers probably can be said to have been The Last Poets and Gil Scott-Heron with their recordings in the latter 1960s and earliest 1970s (such as Scott-Heron’s famous "The Revolution Will Not Be Televised" and "Whitey on The Moon"), but, slightly later, MCs (from "Master of Ceremonies") would improvise rhymes over the beats created by dancehall and club DJs. Early raps were frequently merely a sequence of boasts, or attempts to upstage the other MCs. See roots of rap music for earlier forms that also contributed to rap.

The first record of this new school of rap was 1979’s "King Tim III" by the Fatback Band (featuring the rapper King Tim III). The Sugarhill Gang followed the same year with "Rapper’s Delight", that became a major hit and is based on Chic’s oft-sampled disco track "Good Times". In 1981 Blondie became the first act popular with large and largely-Caucasian audiences to feature a contemporary-style rap sequence in their hit "Rapture." Rap is a way of poetically expressing oneself while rhyming on a beat.

Descendents and influence :
Rapping can be seen as one of the four elements of hip hop : MCing (rapping), DJing (mixing, cutting and scratching), graffiti (tagging), and breakdancing. However, in the course of rap’s history, new musical styles developed that use rapping - especially rapcore, also known as rap/rock or rap/metal, first introduced by crossover pioneer Run-DMC’s collaboration with Aerosmith in 1986. Some alternative rap has musically very little to do with hip hop and rap music. Often consisting of bizarre soundscapes and vivid lyrics, abstract hip-hop has developed, largely in the underground.

Music outside of the United States has taken the rap style and blended it with completely different elements. Japanese dance music, for example, often uses rapping to complement or break up the singing parts, with lyrics containing upbeat themes set to energetic rhythms and clean, warm synths. A new offshoot of garage techno, dubbed Grime, has emerged in Britain, featuring acts like Dizzee Rascal and Wiley.

The importance of rhyme :
Undoubtedly, the most important element of rap lyrics is rhyme. In other forms of poetry, rhymes that span many syllables are often considered whimsical but in hip hop, the ability to construct raps with large sets of rhyming syllables is considered a sign of intelligence and achievement. For the same reason, rap music is sometimes referred to as "street poetry" or "street rhyme". To accomplish rhymes of this sophistication, rappers can use single rhyming words (intellectual/ineffectual) or they can use multiple words whose constituent syllables rhyme (octoroon/Doctor Dooom). Rap lyrics often contain long series of lines each of which rhyme with each other. Occasionally, entire songs are composed in this fashion where all lines rhyme with each other. Of course, the more intricate the rhymes are, the more abstract the song becomes. This is because the more focus given to impressive rhyming, the harder it becomes to write coherently. Battle raps can be written with complex rhyming techniques easier than raps that tell a story or convey a message because a battle rap can employ a vast array of metaphors to conjure images of rapper to rapper combat.

Rhyme is also integral to Freestyle battles. These contests pit two rappers together to lyrically insult and intimidate each other with impromptu lyrics. The ability to construct clever rhymes to insult the opponent "off the top of the dome" (dome being slang for head) is a critical skill to winning these contests.