The term “mash-up” or “bootleg” (or, more commonly, just “boot”) describes the result of mixing together two or more records to create a whole new track. Though originally performed live using turntables and DJ mixers, recent advances in sequencing software have taken this art-form to a whole new level. This document outlines how mash-ups can be made using the software package Tracktion. Link.
Boot Camp – Mashing for Beginners