With their two previous albums, Run-DMC and King of Rock, Run-DMC made a name for themselves as hip-hop innovators. Where their predecessors had focused on making dance music (Afrika Bambaataa's "Planet Rock" and most songs by The Fat Boys come to mind), Run-DMC wanted to build their rep on lyrical skill. They optimized this by wearing all black clothes, fedoras, and Adidas attire. Think of them as the turtlenecked Steve Jobses of rap. Their raps were hardcore: the beats and the samples served to intensify their boasts, not just to create something you could dance to.
In looking for the hardest, most aggressive sounds to rap over, Run-DMC often turned to distorted rock guitar. "Rock Box," "Raising Hell," and "King of Rock" are some of the most in-your-face examples, but "It's Tricky" (which samples "My Sharona") and "Walk This Way" are more familiar ones.