Hip hop recently celebrated its 50th anniversary. What started off as an underground movement in the 1970s has blossomed into a global phenomenon with no end in sight. How has hip hop managed to not stop after all these years? Why were those who kept calling it a fad so completely wrong? Guest Todd Boyd has curated a comprehensive book called Rappers Deluxe: How Hip Hop Made the World that chronicles hip hop's defining moments each decade. Using photographs, movie posters, fine art, album covers, film and sports stills, he paints an often misunderstood  portrait of hip hop's influences. Even the word hip hop is often thought to denote the music, but as Boyd describes it, the culture encapsulates much more.  Listen to this sonic journey into hip hop's origins.