A chordophone is a musical instrument that makes sound by way of a vibrating string or strings stretched between two points. It is one of the four main divisions of instruments in the original Hornbostel-Sachs scheme of musical instrument classification. What many would call string instruments are classified as chordophones.
Violins, guitars, lyres, and harps are examples. However, the word also embraces instruments that many would hesitate to call string instruments, such as the musical bow and the piano (which, although sometimes called a string instrument, is also called a keyboard instrument and a percussion instrument).
Hornbostel and Sachs’ criterion for determining which sub-group an instrument falls into is that if the resonator can be removed without destroying the instrument, then it is classified as 31. The idea that the piano’s casing, which acts as a resonator, could be removed without destroying the instrument, may seem odd, but if the action and strings of the piano were taken out of its box, it could still be played. This is not true of the violin, because the string passes over a bridge located on the resonator box, so removing the resonator would mean the strings had no tension.
31 = Simple Chordophones.
32 = Composite Chordophones.