Prepared guitar

A prepared guitar is a guitar that has had its timbre altered by placing various objects on or between the instrument's strings, including other extended techniques. This practice is sometimes called tabletop guitar, because many prepared guitarists do not hold the instrument in the usual manner, but instead place the guitar on a table to manipulate it.

A prepared guitar

The idea of altering an instrument's timbre through the use of external objects has been applied to other instruments as well, most notably John Cage's prepared piano, which preceded the prepared guitar.