The guqin (古琴), also traditionally referred to simply as qin, is a traditional Chinese musical instrument. It belongs to the zither family of instruments. The qin is not to be confused with the guzheng, another Chinese instrument from the zither family.

As a fretless type of zither, its 7 strings are capable to producing about 4 octaves of sound, depending on the technique employed. Ancient guqins are sometimes 5-stringed.

The most revered of all Chinese musical instruments, the qin has been in existence for some 3000 years. There are numerous references to the qin in the old Chinese classics that pre-date Confucious, but it is clear that these refer to the instrument in a prototypical or earlier form, certainly not the instrument that is recognised as a qin in contemporary times. The form of the qin that is recognizable today appears to have been set around the late Han dynasty, where a contemporaneous document "Qinfu" describes the instrument in a recognizable form. There are no specimens surviving from that era that have been verified. The earliest surviving "qin" have been reliably dated to the middle and late Tang periods.

Traditional qin music was written in tabulatures, with the most recent classical form being settled around the 12th century CE. A earlier form of music notation from the Tang era survives in just one manuscript, dated to the 10th century CE. Whilst the qin followed a certain grammar of acoustic in its construction, its external form could and did take on a huge amount of variation, whether it be from the embellishments or even the basic structure of the instrument. Qin tabulatures from the Song era onwards have catalogued a menagerie of qin forms. All, however, obey very basic rules of acoustics and symbolism of form.

The sound chamber of the qin is constructed with 2 boards of wood, typically of differing wood types. The top board is usually made of "wutong" from the Chinese parasol tree, while the belly is made of "nan mu" (catalpa wood). There are 2 sound holes in the belly, as the playing techniques of the qin employ the entire surface of the top board. The boards are joined using a "hinge joint" method to produce the typically mellow sounds of the qin. Lacquer from the Chinese lacquer tree is then applied to the surfaces of the qin, mixed with various types of matrix, the most common being "lujiao shuang", the remains of deer antler after the glue has been extracted.

琴棋書畫 (qin qi shu hua) refers to the Four Essential Arts of the Chinese Scholar, wherein 琴 qin/music refers specifically to guqin. [This phrase is a rather late invention of the Song period (according to the Wu Zhi Zhai Qinpu), so it is not clear how essential it was to the pedagody of earlier scholar classes.]

In 2003, guqin music was proclaimed one of the Masterpieces of the Oral and Intangible Heritage of Humanity by UNESCO.