"Gamelan is a spirit, not an object," says noted Indonesian musician Sapto Raharjo, "the instruments are just the medium. A gamelan is often desicribed as a gong-chime percussion orchestra. These beautiful instruments have their origins in the islands of Java and Bali. Unlike the western orchestra, which features predominantly winds and strings, the gamelan is dominated by percussion instruments, although plucked and bowed stings, flutes, and singing are also important. The instruments of a gamelan are usually built as a set. Each set has a characteristic tuning which may be unique or may be copied from another gamelan. The bronze instruments are produced by a complex process of casting and forging.

When the full gamelan is playing, the many instruments and voices blend to create a complex texture. The ethnomusicologist Mantle Hood described this texture as stratified polyphony, characterizing it in terms of layers of sound moving semi-independently at different speeds. Others have used the term heterophony, implying that the individual parts are simultaneous variants of the same melody.

The effect of gamelan on modern western music has been important, influencing composers ranging from Debussy to Steve Reich. The first gamelan to arrive in the U.S. came to Chicago as part of the the Columbia Exposition of 1893. This gamelan is still housed at the Field Museum in Chicago. Eventually, through an expanding interest in ethnomusicology, gamelan instruments appeared on University campuses. Through the efforts of composer/instrument builders such as the great American composer Lou Harrison, gamelan began to play a significant role in the contemporary music scene with its increasing emphasis on world music influences. Today gamelan instruments are found throughout the world, with many, many active ensembles in the U.S.

Gamelan music often includes the following four elements: 1) A cyclical structure. Marked by gongs of various sizes, pitches and timbres, this "colotomic" structure forms a framework for the balungan (literally "skeleton") which is a basic melody played in several octaves on metallophones that have seven or more keys apiece. 2) Instruments with greater ranges and vocals provide elaboration that is related more or less directly to this balungan, converging with it at regular intervals, and is typified by a high degree of patterning. 3) Each of the elaborating parts has a distinct idiom including a stock of patterns (cengkok) and ways of varying these patterns (wiled). 4) Finally, the ensemble is guided by drumming that regulates tempo, treatment, and transitions.