Battle rap (also known as rap battling) is a type of rapping that includes bragging and boasting content. Battling can occur on recorded albums, though rap battles are often recited or freestyled spontaneously in live battles, "where MCs will perform on the same stage to see who has the better verses".
Battle rap is described by 40 Cal in the book How to Rap as "extracurricular" and he compares it to the dunk contest in the NBA. Rap battles are often written solely for the purpose of impressing people with technically inventive rapping, and knowing a wide variety of rapping styles and a wide range of MCs is recommended. Some MC's started out writing mostly battle raps and battling other MCs before they began making records.
The modern rap battle is generally believed to have originated in the East Coast hip hop scene in the late 1970s. One of the earliest and most infamous battles occurred in December 1982 when Kool Moe Dee challenged Busy Bee Starski - Busy Bee Starski's defeat by the more complex raps of Kool Moe Dee meant that "no longer was an MC just a crowd-pleasing comedian with a slick tongue; he was a commentator and a storyteller" thus, rendering Busy's archaic format of rap obsolete, in favor of a newer style which KRS-One also credits as creating a shift in rapping in the documentary Beef.
In the 1980s, battle raps were a popular form of rapping - Big Daddy Kane in the book How to Rap says, "as an MC from the '80s, really your mentality is battle format... your focus was to have a hot rhyme in case you gotta battle someone... not really making a rhyme for a song". Battle rapping is still sometimes closely associated with old school hip-hop - talking about battle rapping, Esoteric says, "a lot of my stuff stems from old school hip-hop, braggadocio ethic".