Korea is renowned for its different types of zithers. A "zither" is a general term used to describe a family of stringed instruments whose strings stretch over but not beyond a resonating chamber. A Western example would be the hammered dulcimer. Zithers can be played in a variety of ways: plucked, bowed, hammered or strummed.
The ajaeng is a zither with seven to nine strings, played with a rosined bow. The player draws the bow horizontally across the strings, producing a thick, rasping sound. Variations on the ajaeng are used for different purposes: the seven-stringed ajaeng adds texture to the bass section of an orchestra; the eight-stringed is more often used in folk and chamber music; and the nine-stringed ajaeng is a solo instrument with a more melancholy tone.
The gayageum is a zither, related to the Chinese and Japanese cheng and koto, is the most well-known of Korean stringed instruments. Its twelve silk strings stretch across twelve moveable bridges. Unlike the bowed ajaeng, the gayageum is plucked. The musician uses his or her left hand to pluck the strings while moving the twelve bridges to control pitch. In modern times, Korean musicians have explored the versatility of the gayageum by adding more strings --- today, pieces written for 17 to 25 stringed gayageum are common.
The geomungo, another zither, is traditionally the most honored of Korean instruments. It once enjoyed great popularity among the class of scholars. Its majestic tones are created by plucking the six strings with a bow while the left hand presses the strings to alter pitch.
The haegeum is a Korean fiddle with only two strings. It was once played all across Asia and is comparable to the Turkish kamenche, a three-stringed fiddle that is probably related to its Korean counterpart. The haegeum is played by resting the end of the fiddle on one's knee, bowing with the right hand and pressing down on the fingerboard with the left hand to control pitch.
The yanggeum is a stringed instrument, but it is played like a percussion instrument. A dulcimer, it is thought to have been introduced from Europe because it is the only Korean instrument with steel instead of silk strings, and the only one played by lightly hitting the strings with a bamboo bow.