This term is used in two different ways. It is synonymous with certain innovative electronic forms of pop music including so-called Intelligent Dance Music (IDM). Most of this music is primarily note based whilst using sound-based elements and techniques. It is also used as a term for a type of sound-based music that has been created as a reaction to more elitist forms of sound-based music. Here the reaction can be found in the type of materials used, such as unwanted sounds including noise or the glitch sound created in CDs that are not working properly and other sorts of digital or analogue detritus thus creating a lo-fi effect that exists independently of most pop and art music developments. (See also the electronica discussion in chapter 1)