Russell Simmons is the most important businessman in the history of rap music. As co-founder of the Def Jam label, Simmons' street-friendly taste and marketing savvy helped bring hip-hop crashing into the mainstream of American culture and mass media. He's often been compared to Motown impresario Berry Gordy, but there's one important difference: Where Gordy strove to make assimilationist R&B that would be considered respectable by pop audiences, Simmons ensured that his artists remained as uncompromisingly rebellious as possible. That attitude made hip-hop a music of choice for a generation of teenagers simply by staying true to its roots; it was a multi-cultural phenomenon that succeeded -- more or less -- on its own terms. Simmons was the entrepreneur who shepherded rap music into big business, gradually building his own communications company into the largest black-owned enterprise in the industry. By the time he sold Def Jam for 100 million dollars in 1999, he was one of the most respected figures in the rap business, and continued to take an active interest in shaping the culture's future direction.