Editing String instrument (section)

== Production of multiple notes ==
[[File:Ottoman musical string instrument at the Debbane Palace museum.jpg|thumb|Arab string musical instrument on display at the [[Debbane Palace]] museum, [[Lebanon]]]]
A single string at a certain tension and length only produces one note. To produce multiple notes, string instruments use one of two methods. One is to add enough strings to cover the required range of different notes (e.g., as with the [[piano]], which has sets of 88 strings to enable the performer to play 88 different notes). The other is to provide a way to ''stop'' the strings along their length to shorten the part that vibrates, which is the method used in guitar and violin family instruments to produce different notes from the same string. The piano and harp represent the first method, where each note on the instrument has its own string or [[Course (music)|course]] of multiple strings tuned to the same note. (Many notes on a piano are strung with a "choir" of three strings tuned alike, to increase the volume.) A guitar represents the second method—the player's fingers push the string against the fingerboard so that the string is pressed firmly against a metal fret. Pressing the string against a fret while plucking or strumming it shortens the vibrating part and thus produces a different note.

Some zithers combine stoppable (melody) strings with a greater number of "open" harmony or chord strings. On instruments with stoppable strings, such as the violin or guitar, the player can shorten the vibrating length of the string, using their fingers directly (or more rarely through some mechanical device, as in the [[nyckelharpa]] and the hurdy-gurdy). Such instruments usually have a fingerboard attached to the neck of the instrument, that provides a hard flat surface the player can stop the strings against. On some string instruments, the fingerboard has [[fret]]s, raised ridges perpendicular to the strings, that stop the string at precise intervals, in which case the fingerboard is also called a ''fretboard''.

Moving frets during performance is usually impractical. The bridges of a [[Koto (instrument)|koto]], on the other hand, may be moved by the player occasionally in the course of a single piece of music. Many modern Western harps include levers, either directly moved by fingers (on Celtic harps) or controlled by foot pedals (on orchestral harps), to raise the pitch of individual strings by a fixed amount. The Middle Eastern zither, the [[Qanun (instrument)|qanun]], is equipped with small levers called ''mandal'' that let each course of multiple strings be incrementally retuned "on the fly" while the instrument is being played. These levers raise or lower the pitch of the string course by a microtone, less than a half step.