Short answers, pulled from the story.
Rapping originated in the Bronx, New York City, in the early 1970s, growing out of announcements made by DJs and MCs over the microphone at parties. It became part of popular music later that decade, with the first rap recording released by the Fatback Band a few weeks before the Sugarhill Gang in 1979.
Scholars identify three core components of rap: content (the lyrics and what is being said), flow (the rhythm and rhyme), and delivery (cadence and tone). Flow is further broken down into rhyme, rhyme schemes, and rhythm, with staying on the four-beat musical backdrop considered central to the form.
Rakim is credited by Kool Moe Dee and many other artists with creating the concept of flow as it is understood in hip-hop. Before Rakim's influence took hold in 1986, the practice was called rhyming or cadence; Rakim also introduced the technique of placing rhymes inside the line rather than only at its end.
Precursors to rap include the West African griot tradition of rhythmic storytelling over drums, the Black sermonic tradition, blues music (with recorded rapping in the blues documented as early as the 1920s), jazz poetry, and African-American insult games like playing the dozens. The Jubalaires' gospel songs from 1941 and 1946 are also considered early precursors.
The English verb rap dates to at least 1541 in print, originally meaning to utter something sharply or vigorously. In African American vernacular, it evolved by the 1960s into a slang term meaning to converse openly, and Isaac Hayes used it in a musical context on his 1970 album "...To Be Continued". The claim that rap stands for Rhythm And Poetry is considered a backronym, not the true origin.
Spanish rapper Domingo Edjang Moreno, known by his alias Chojin, holds the record for fastest rapping. He rapped 921 syllables in one minute on the 23rd of December 2008.