Electronic instruments are ones that begin with an electronic generated oscillator of some kind. An electronic guitar is NOT an electronic instrument. It is a string instrument that has had its timbre altered by electronic effects. The earliest usable electronic instrument was the Hammond organ. Another early electronic instrument is the Theremin, famous for its use in early horror and suspense films. The synthesizer is the most well known of electronic instruments. But, bear in mind that some synthesizers are really not electronic ones as they generate the sound from recordings rather than from oscillators. The dynamic level of a synthesizer is hard to compare to the other families of timbres because it relies solely on amplification, which can be turned up or down. Electronic instruments have the widest variety of sounds possible. In fact, it is an infinite variety of possibilities.