The yueqin (Chinese: 月琴, pinyin: yuèqín; also spelled yue qin, or yueh-ch'in; and also called moon guitar, moon-zither, gekkin, la ch'in, or laqin) is a traditional Chinese string instrument. It is a lute with a round, hollow wooden body which gives it the nickname moon guitar. It has a short fretted neck and four strings tuned in courses of two (each pair of strings is tuned to a single pitch), generally tuned to the interval of a perfect fifth. Occasionally, the body of the yueqin may be octagonal in shape. photo
According to legend, the instrument was invented in China during the Qin dynasty. It is an important instrument in the Beijing opera orchestra, often taking the role of main melodic instrument in lieu of the bowed string section.
A similar Japanese instrument, called the gekkin, was formerly used in Japan. Another very similar instrument, called đàn đoản or đàn tứ, is occasionally used in Vietnam.
The frets are arranged rather like those on a mountain dulcimer, so that the instrument is diatonic (i.e. it can't play every semitone).
The strings on the traditional form of the instrument are made of silk (or nylon) and plucked with a rather long, sharp plectrum, which is sometimes attached to the instrument with a piece of cord.
There is no sound-hole, but inside the sound box are one or more strands of (brass?) wire attached only at one end, so that they vibrate, giving the instrument a particular timbre and resonance.
There's no bridge or saddle; the strings are simply attached to the anchor at the base of the instrument.
Three-string instruments are often tuned A D a, and four-string instruments are often tuned to A D a d.
The anchor on modern instrument may have up to 5 holes, so it can be strung and tuned as a 3- or 4-string instrument. The nut, at the peghead end of the instrument, is filed with notches appropriate to the number and position of the strings.
Modern yueqins are often played with a guitar pick.