Scratch is a DJ technique that involves manipulating vinyl records on a turntable to create rhythmic and percussive sounds. DJs use their fingers to move the record back and forth, creating a "scratching" sound that can be incorporated into a mix. Scratch has been a fundamental part of hip hop since its inception and has influenced many other genres of music. It requires a high level of skill and creativity, making it a popular form of musical expression for DJs and producers.