This is a list of instruments by Hornbostel-Sachs number, covering those instruments that are classified under 31 under that system. This category includes all instruments consisting of a simple string bearer and strings. An additional resonator may be present, but it is not integral, so removing it should not destroy the instrument - the resonator must not be supporting the strings.
This category includes musical bows, zithers and some keyboard instruments like the piano and harpsichord.
These instruments may be classified with a suffix, based on how the strings are caused to vibrate.