Electronic music is music that employs electronic musical instruments and electronic music technology in its production. In general a distinction can be made between sound produced using electromechanical means and that produced using electronic technology. Examples of electromechanical sound producing devices include the telharmonium, Hammond organ, and the electric guitar. Purely electronic sound production can be achieved using devices such as the Theremin, sound synthesizer, and computer.
Electronic music was once associated almost exclusively with Western art music but from the late 1960s on the availability of affordable music technology meant that music produced using electronic means became increasingly common in the popular domain. Today electronic music includes many varieties and ranges from experimental art music to popular forms such as electronic dance music.
Source: Wikipedia article
All electroacoustic music is made with electronic technology. Many works in the field are concerned with those aspects of sonic design that remain inaccessible to either traditional or electronic musical instruments played live. Some electroacoustic compositions make use of sounds not available to typical acoustic instruments, such as those used in a traditional orchestra. These sounds sources may be prerecorded sounds, transformed sound recordings, or synthesized timbres.
Some electroacoustic music places less emphasis on the “traditional” concerns of score-based music — rhythm, meter, harmony, and melody — and instead tends to explore the interplay of gesture and texture. Electroacoustic compositions can also utilize the manipulation of sound in space, using various loudspeaker based spatialisation techniques.
Source: Wikipedia article Electroacoustic Music