A loop in music is a section of the music that repeats itself continuously until receiving a signal to either stop or move on to the next section. A loop can be assigned to a single instrument or to a group of instruments. Compositionally, loops are used for a variety of purposes. For example, they may function as formal bass patterns over which a composition is built, or they may suppy a long but consistently repeating series of chords used to define the harmony for independently composed bass and melody lines. For many computer-based music-makers the loop's most popular implementation is the drum loop, a rhythmic pattern of one or more measures of percussion sounds that can be repeated unchanged for simple lines or mixed & matched with other loops for more life-like variation.