A gamelan is a traditional musical ensemble from Indonesia which usually use metalofon, gambang, gendang, and gong. The term of gamelan is refers to the instrument / tool, which is a whole unified that is realized and sounded together.

Gamelan often accompanies dance, wayang (puppet performances), or rituals and ceremonies. Typically players in the gamelan will be familiar with dance moves and poetry, while dancers are able to play in the ensemble. In wayang, the dalang (puppeteer) must have a thorough knowledge of gamelan, as he gives the cues for the music. Gamelan can be performed by itself in "klenengan" style, or for radio broadcasts, but concerts in the Western style are not traditional.

There is a Javanese saying, "It is not official until the gong is hung" so Gamelan's role in rituals is so important in java. Some performances are associated with royalty, such as visits by the sultan of Yogyakarta. Certain gamelans are associated with specific rituals, such as the Gamelan Sekaten, which is used in celebration of Mawlid an-Nabi (Muhammad's birthday). In Bali, almost all religious rituals include gamelan performance. The Catholic church in Indonesia is also used Gamelan in the ceremonies. Certain pieces are designated for starting and ending performances or ceremonies. When an "ending" piece (such as "Udan Mas") is begun, the audience will know that the event is nearly finished and will begin to leave. Certain pieces are also believed to possess magic powers, and can be used to ward off evil spirits.

There are many instrument that used in gamelan like kempul, gong, siyem, bonang, suling, kempyang, kethuk, kenong, saron, slenthem, kendang, celempung, rebab, gambang, gender.