In the three decades since Kool Herc first put the same record on two side-by-side turntables, DJs have moved out of city parks, house and block parties, and the darkened booths of nightclubs, and onto center stage, performing before admiring crowds of thousands. They have not only given rise to hip-hop and house—DJs have influenced fashion, film, TV, and more.With On the Record, Scratch DJ Academy, the premiere institution for DJ education, brings together years of trainin...