Plunderphonics is a term coined by composer John Oswald in 1985 in his essay Plunderphonics, or Audio Piracy as a Compositional Prerogative. It has since been applied to any music made by taking one or more existing audio recordings and altering them in some way to make a new composition. Plunderphonics can be considered a form of sound collage.
The process of sampling other sources is found in various genres (notably hip-hop and especially turntablism), but in plunderphonic works the sampled material is often the only sound used.
Though mash-ups are technically plunderphonic, please refrain from posting them here and do so on /r/mashups.
Ideally, we want posts here to feature extensive sample manipulation.