A collective name for various, mainly percussive, instruments which are used in the Indonesian gamelan orchestra. It is the main element of Indonesian traditional music.

 Each gamelan is slightly different. However, they all have the same organisation, based on different instrumental groups with specific orchestral functions. The instruments in a gamelan are composed of sets of tuned bronze gongs, gong-chimes, metallophones, drums, one or more flutes, bowed and plucked string instruments, and sometimes singers. In some village gamelan, bronze is sometimes replaced by iron, wood or bamboo. The most popular gamelan can be found in Java and Bali.

In Indonesian traditional thinking, the gamelan is sacred and is believed to have supernatural power. Both musician and non-musicians are humble and respectful to the gamelan. Incense and flowers are often offered to the gamelan. It is believed that each instrument in the gamelan is guided by spirits. Thus, the musician have to take off their shoes when they play the gamelan. It is also forbidden to step over any instrument in a gamelan, because it might offend the spirit by doing so. Some gamelan are believed to have so much powers that playing them may exert power over nature. Others may be touched only by persons who are ritually qualified.

In Javanese gamelan, the most important instrument is the gong ageng.