The theremin is an electronic musical instrument that is played without physical contact by the performer. It is played by moving the hands through an electromagnetic field, which controls the pitch and volume of the sound. The theremin was invented in 1919 by Leon Theremin, a Russian physicist and inventor. It is one of the earliest electronic musical instruments and is considered to be one of the most unique and expressive. The theremin has been used in a variety of musical genres, from classical to experimental music, and has been featured in numerous films and television shows.