A string instrument (or stringed instrument) is a musical instrument that produces sound by means of vibrating strings. In the Hornbostel-Sachs scheme of musical instrument classification, used in organology, they are called chordophones. The most common string instruments in the string family are violin, cello, viola, double bass, mandolin, banjo, guitar, and harp.
All string instruments produce sound from one or more vibrating strings, transferred to the air by the body of the instrument (or by a pickup in the case of electronically-amplified instruments). They are usually categorized by the technique used to make the strings vibrate (or by the primary technique, in the case of instruments where more than one may apply.) The three most common techniques are plucking, bowing and striking. Plucking (Italian: pizzicato) is used as the sole method of playing, on instruments such as the banjo, guitar, harp, lute, mandolin, oud, sitar, and either by a finger or thumb, or by some type of plectrum.
This category includes the keyboard instrument the harpsichord, which formerly used feather quills (now plastic plectra) to pluck the strings.