Well, I'm no jazz historian, but pre-bop is what came before bop. As in be-bop. In the days of the big bands people wanted a big sound, composed mostly of horns and other such nonsense. Pre-bop borrows from jazz basics to create a simple, yet complex sound with rhythm instruments like guitar, piano, and bass. Eventually, all this lead to rock and roll and Weezer. Yeah, that's right, punk. You steppin`?