The shamisen is similar in length to a guitar, but its neck is much slimmer and without frets. Its drum-like rounded rectangular body, known as the dō, is covered front and back with skin in the manner of a banjo, and amplifies the sound of the strings. The skin is usually from a dog or cat, but in the past a special type of paper was used and recently various types of plastics are being tried. On the skin of some of the best shamisen, the position of the cat’s nipples can still be seen. 
The three strings are traditionally made of silk, or, more recently, nylon. The lowest passes over a small hump at the “nut” end so that it buzzes, creating a characteristic sound known as sawari (somewhat reminiscent of the “buzzing” of a sitar, which is called jawari). The upper part of the dō is almost always protected by a cover known as a dō kake, and players often wear a little band of cloth on their left hand to facilitate sliding up and down the neck. This band is known as a yubikake. There may also be a cover on the head of the instrument, known as a tenjin
History and genres
The shamisen derives from the sanshin (三線, a close ancestor from the southernmost Japanese prefecture of Okinawa in the 16th century and one of the primary instruments used in that area), which in turn evolved from the Chinese sanxian, itself deriving ultimately from Central Asian instruments.
The shamisen can be played solo or with other shamisen, in ensembles with other Japanese instruments, with singing such as nagauta (長唄), or as an accompaniment to drama, notably kabuki (歌舞伎) and bunraku (文楽). Both men and women traditionally played the shamisen.
The most famous and perhaps most demanding of the narrative styles is gidayū, named after Takemoto Gidayū (1651-1714), who was heavily involved in the bunraku puppet-theater tradition in Osaka. The gidayū shamisen and its plectrum are the largest of the shamisen family, and the singer-narrator is required to speak the roles of the play, as well as to sing all the commentaries on the action. The singer-narrator role is often so vocally taxing that the performers are changed halfway through a scene. There is little notated in the books (maruhon) of the tradition except the words and the names of certain appropriate generic shamisen responses. The shamisen player must know the entire work perfectly in order to respond effectively to the interpretations of the text by the singer-narrator. From the 19th century female performers known as onna-jōruri or onna gidayū also carried on this concert tradition.
In the early part of the 20th century, blind musicians, including Shirakawa Gunpachirō (1909-1962), Takahashi Chikuzan (1910-1998), and sighted ones such as Kida Rinshōei (1911-1979), evolved a new style of playing, based on traditional folk songs (“min’yō”) but involving much improvisation and flashy fingerwork. This style – now known as Tsugaru-jamisen, after the home region of this style in the north of Honshū – continues to be relatively popular in Japan. The virtuosic Tsugaru-jamisen style is sometimes compared to bluegrass banjo.
Kouta (小唄) is the style of song learned by geisha and maiko. Its name literally means “small” or “short song,” which contrasts with the music genre found in bunraku and kabuki, otherwise known as nagauta (長唄) (long song).
Jiuta (地唄), or literally “earthen music” is a more classical style of shamisen music.