A koto is a Japanese stringed instrument which is a common feature in traditional Japanese music. The distinctive twang of the koto may be familiar to you, if you have heard any performances of Japanese music, especially traditional and folk music. Like many instruments, the koto may be played alone, or as part of an ensemble, and there are a number of different styles of koto and schools of koto playing, making this a very diverse instrument.
Historical evidence suggests that the koto is probably descended from the Chinese instrument known as a guqin, which was first brought to Japan in the 8th century CE. The koto is also very similar to the Western zither. Through the 17th century, kotos were primarily heard in court performances, often by solo players; after this point, people began to adapt the koto for traditional folk music as well, and people of all classes and levels of ability played the koto in a wide variety of settings.
The instrument takes the form of a long oblong box, with two fixed bridges on either side, to which are attached anywhere between one and 17 silk strings, although 13 is the most common number. A series of movable wooden or ivory bridges can be adjusted for tuning, allowing musicians to create a specifically desired sound, and the instrument is played with picks which are worn on the fingers of one hand.
Traditionally, koto is played in a seated position on the floor. This stringed instrument has come to be associated by many people with geisha, Japanese entertainers who may offer song and dance performances accompanied by traditional instruments including the koto. Modern musicians have also attempted to adapt the koto to make it usable in a range of modern compositions, many of which are radically different from traditional Japanese music.
You may be able to hear a koto performance in your area, if you happen to live in a large urban area or a region with a big Japanese population; a good source of information about performances on koto and other Japanese instruments would be a cultural center or theatre. You can also find numerous recordings of koto available at music stores and online, if you are interested in getting a sense of the sound of the instrument. For people who are interested in learning to play koto, a store which sells musical instruments may be a good place to start, as the staff can help connect interested musicians with instructors.