Yesterday—August 11, 2013—marked the 40th anniversary of DJ Kool Herc's very first block party in the Bronx, where the then-sixteen-year-old kid started a revolution that wound up turning popular music completely on its head. Herc, who went by Clive Campbell back then, didn't know it at the time, of course, but over the following 40 years, his early form of hip-hop birthed that day would eventually pump out legends by the names of Kane and Rakim, Premier and Red Alert, Biggie and 'Pac, and Jay Z and Lil Wayne.

The genre that started out chopping up break beats and soul and disco samples into a new form of proto-dance music has shifted mightily every five years or so since, turning from community event dance music to battlegrounds for aspiring rhymers, from politically-conscious calls to arms to coke-dealing, crack-slinging portraits of the inner city, from telling stories about girls to—well, okay, some things never change. But one thing that is undeniable is that the movement that began 40 years and a day ago is markedly different in 2013 in almost every way. XXL spoke to some of the most important rappers and producers throughout the years—including some that performed at Herc's celebration last Saturday (August 10) at SummerStage in New York City's Central Park, which marked the event—about the changes the genre has gone through in the past four decades, and what that might mean for the future. —Dan Rys (@danrys)