A Chordophone is any musical instrument which produces sound primarily 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 most westerners would call string instruments are classified as chordophones, violins, guitars, lyres, harps, for some examples. However, the word also embraces instruments that many westerners 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-Sachs divides chordophones into 55 main groups: instruments without a resonator that is an integral part of the instrument (which have the classification number 31); and instruments with such a resonator (which have the classification number 32). Most western instruments fall into the second group, but the piano and harpsichord fall into the first. 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.

Electric string instruments often have an electromagnetic pickup with which the sound can be amplified. The electric guitar is the most famous example, but there are new instruments like the overtone koto who make use of the new possibilities that pickups offer

How chordophones work

Chordophones make their sound when a stretched string vibrates. There is usually something that makes the sound reverberate such as the body of a guitar or violin. The strings are set into motion by either plucking (like a harp), strumming (like a guitar) or by rubbing with a bow (like a violin or cello). Some common chordophones are the banjo, the dulcimer, the fiddle, the guitar, the harp, the lute, the piano, the ukulele, the viola and the violin.

A chordophone is not classified as any instrument that can play a chord of three or more notes at once, such as a harmonica or xylophone.

	Hornbostel-Sachs system of musical instrument classification
Idiophone | Membranophone | Chordophone | Aerophone | Electrophone List of musical instruments by Hornbostel-Sachs number