In the context of musical performance, air instruments are imaginary musical instruments for which people mimic the sound-producing gestures in the air without touching a real instrument. In simple words air instruments are the musical instruments which could be played without touching the real instrument. Air instruments include:
- air guitar - for electric guitar or acoustic guitar;
- air bass - for bass guitar;
- air drums - for snare drums, bongos or bass drum, or most commonly air drum set often with double bass pedals ;
- air keyboards - such as air piano for piano;
- air violin - for violin or cello;
- air flute - for flute (or piccolo);
- air xylophone - for the xylophone;
- air trumpet - for trumpet (as opposed to car/boat air trumpet horns);
- air trombone - for trombone.
The playing of air instruments has been documented through the 20th century (see: Air guitar). However, no sources have been found that exclude the playing of air instruments in ancient times, during private performances, such as for air flute or air lyre (for lyres or harps). One gesture musical instrument which won first place in the 2008 Chicago Makers Faire at the Chicago's Museum of Science and Industry is an instrument named Airheads that demonstrates the ability to simulate different musical instrument using only your hand gestures moving in the air.
Invented by John R. Folaron  a gesture musical instrument which won 1st place in the 2008 Chicago Makers Faire at the Chicago Museum of Science and Industry. This instrument, named Airheads, demonstrates the ability to simulate different musical instruments using only hand gestures moving in the air. Using the instrument as a drummer would has been achieved very effectively for use in live concert performances. Ref makezine.com 2008 makers fair Chiciago - Makers Faire also Austin Texas, Music Makers Fair, and 
For the air piano, both left and right hands can be used, as well as moving the feet to mimic pressing the piano floor pedals.
The AirPiano is a musical computer interface (from 2007) which allows playing and controlling software instruments simply by moving hands in the air over the device, connected by USB cable. Above the AirPiano is an invisible matrix of virtual keys plus faders, each pre-assigned with MIDI messages and waiting to be triggered, via infrared sensors. The length of each triggered note is determined by the time the hand is placed over the corresponding virtual key. Beyond the feedback of the sounds changing, hand placement is also confirmed by LED feedback. The first version of AirPiano generated polyphonic sound, with 24 keys using 8 faders.
Besides the gestures to accompany real violin performances, playing the air violin can also be a form of sarcasm, to indicate that another person seems to be rambling with a sob story or whining excessively, in self-pity.
- Rolf Godøy1 et al., "Playing 'Air Instruments'...", 2006 (see: References).
- Steven Appleby et al., Better Living Through Air Guitar, 2005.
- "airpiano", 2007, webpage: www.airpiano.de: in patent note, the word "filled" is interpreted as "filed".
- "Student creates AirPiano", Ben Rogerson, MusicRadar.com, 2008-07-01 (Tuesday), webpage: Musicradar-2525.
- "What I wish I could have said to my teachers", Nogie Demirjian, 2002, L.A. Youth, Los Angeles, CA; webpage: LA-Youth-1175.
- Steven Appleby and George Mole, Better Living Through Air Guitar, 2005-03-11, publisher: Piatkus, ISBN 978-0-7499-5094-1, ISBN 0-7499-5094-3.
- Rolf Inge Godøy1, Egil Haga1 and Alexander Refsum Jensenius1, "Playing 'Air Instruments': Mimicry of Sound-Producing Gestures by Novices and Experts", Gesture in Human-Computer Interaction and Simulation, February 2006, University of Oslo, Department of Musicology, Oslo, Norway, ISBN 978-3-540-32624-3.
- Rolf Godøy1 et al., "Playing 'Air Instruments': Mimicry of Sound-Producing Gestures by Novices and Experts", Gesture in Human-Computer Interaction and Simulation, February 2006, webpage: SpringerLink-1152 (HTML, with link to preview or PDF).
- "AirPiano - Musical Interface (AirPiano) - 440TV Video", webpage: 440TV-AirPiano-video.
- "AirHeads - By John R. Folaron Human gesture Musical Midi controller Interface played like a harp or Air Drums ", webpage: www.Air-Instruments.com