Electronic music that does not fall into the new age, techno or dance categories are often referred to as "left-field" or "electronica" (although there are critics who maintain that the term "electronica" is an invention of the media). Styles of electronica include ambient, downtempo, illbient and trip-hop (among countless others, see list of electronic music genres), which are all related in that they usually rely more on their atmospheric qualities than electronic dance music, and make use of slower, more subtle tempos, sometimes excluding rhythm completely.
IDM (an abbreviation for intelligent dance music) is an elusive and confusing genre classification that can only be truly defined by flagbearers and flagburners like Aphex Twin and Autechre.
All electronic music owes at least its historical existence to early pioneers of tape experiments known as musique concrète, such as John Cage, Pierre Schaeffer and Karlheinz Stockhausen, as well as early synthesists like Wendy Carlos, Jean-Michel Jarre, and Morton Subotnick . (See electronic art music).