The evolution of hip hop has been shaped by many different artists, but there’s a case to be made that it came to life precisely on this day in 1973, at a birthday party in the rec room of an apartment building in the West Bronx, New York City. The man who presided over that historic party was the birthday girl’s brother, Clive Campbell – better known as DJ Kool Herc, founding father of hip hop.

DJ Kool Herc’s signature innovation came from observing how the crowds would react to different parts of whatever record he happened to be playing: “I was noticing people used to wait for particular parts of the record to dance, maybe [to] do their specialty move.” Those moments tended to occur at the drum breaks. What Kool Herc decided to do was to use the two turntables in a typical DJ setup not as a way to make a smooth transition between two records, but as a way to switch back and forth repeatedly between two copies of the same record, extending the short drum break that the crowd most wanted to hear. He called his trick the Merry Go-Round. Today, it is known as the “break beat.”

By the summer of 1973, DJ Kool Herc had been using and refining his break-beat style for the better part of a year. His sister’s party on August 11, however, put him before his biggest crowd ever and with the most powerful sound system he’d ever worked. It was the success of that party that would begin a grassroots musical revolution.

DJ Kool Herc is a key contributor to the documentary Rubble Kings, due for UK cinema release from 11th September 2015