In his book ' music of Java ' Jaap Kunst says, "Gamelan is comparable to only two things, moonlight and flowing water. ...mysterious like moonlight and always changing like flowing water ...".
Gamelan music is an integral part of all cultural activities in Java such as wayang kulit (leather puppets) performance, court dance, uyon-uyon (symphony orchestra performance), etc. There are two kinds of laras (tuning) in gamelan, namely slendro (comparable to minor key in Western music) and Pelog (major key). A complete set of gamelan consist of two sets of different instruments of Slendro and Pelog, such as:
Each slendro and pelog set had three gongs. Two big gongs (Gong Ageng) and one gong Suwukan about 90 cm, made from bronze, suspended on a wooden frame. It marks the end of the largest phrase of the melody.