String instruments, also called chordophones, produce their sound by means of vibrating strings made of gut or metal. They are often divided in three families.
Lutes - Instruments in which the strings are supported by a neck and some kind of resonance chamber, gourt, or bout. Included here are both the guitar and the violin.
Zithers or Citres - Instruments that have do not possess a neck and have their strings mounted on their body. This broad defintion includes, besides piano, harpsichord, autoharp and dulcimer, the guzheng from China and the koto from Japan.
Harps - Instruments which have their strings mounted in a right angle to their soundboard. These include the harp and its variations, but not the autoharp, because its strings are not perpendicular to its soundboard. Harps are sometimes regarded as a subgroup of the zither family.
Other classifications focus on the way the sound is produced by the player:
Plucked String Instruments are played by plucking the strings, either with the fingers or with some kind of plucking device, like a plectrum or a feather. Variations and ramifications of both groups are countless and found all over the world, including, besides the well known guitar, mandolin and banjo, also the oud from the Middle East and Arabia, bouzouki and baklama from Greece, the saz from Turkey,the biwa, the koto and the shamisen from Japan, the sanhsien and the pi pa from China, the tanbur from Afghanistan, the icbacarre from Mosambique, the khalam from Senegal, the sitar and the sarod from India, the koboz from Hungary and the mandora from Sweden, to just name a few. Also the harpsichord, which uses feather quills or plectrum like devices to pluck the strings, belongs to this family.
Bowed String Instruments are played with the help of a bow, typically made of horse-hair, nowadays often also of snythetic material. Moving the bow across a string results in a sawing effect which causes the string to vibrate. Popular examples are the violin family (violin, viola, cello, double bass (of the violin family), the erh hu from China, the sarangi from India and the rebab from Arabia. Exotic variants inlcude the nyckelharpa from Sweden and the drehleier or hurdy-gurdy from medieval Europe, where the strings are bowed with the help of a wheel. Bowed String instruments can of course be plucked as well, resulting in a sound known as "pizzicato". The bow may also be used for striking or hitting the string rather than for bowing, which is called "col legno". Some modern instruments like the electric guitar may be can be played with an e-Bow, a hand-held cigarette box sized and battery powered device that creates a magnetic field to make the string vibrate.
Players of Struck String Instruments hit or strike the strings with hammer-like devices or sticks, either by way of a mechanical process (controlled by a keyboard) or by holding the sticks in their hand. The most famous representative of this family are the piano, clavichord and hammered dulcimer. Popular ethnic examples include the Indian santoor and the cimbalom from Eastern Europe. Modern members of this family are the electric guitar variants Chapman Stick, Warr Guitar and Megatar.