The accordion is a box-shaped musical instrument

Musical instrument

A musical instrument is a device created or adapted for the purpose of making musical sounds. In principle, any object that produces sound can serve as a musical instrument—it is through purpose that the object becomes a musical instrument. The history of musical instruments dates back to the...

 of the bellows

Bellows

A bellows is a device for delivering pressurized air in a controlled quantity to a controlled location.Basically, a bellows is a deformable container which has an outlet nozzle. When the volume of the bellows is decreased, the air escapes through the outlet...

-driven free-reed aerophone

Free reed aerophone

A free reed aerophone is a musical instrument where sound is produced as air flows past a vibrating reed in a frame. Air pressure is typically generated by breath or with a bellows.- Operation :...

 family, sometimes referred to as a squeezebox

Squeezebox

The term Squeezebox is a colloquial expression referring to any musical instrument of the general class of hand-held bellows-driven free reed aerophones such as the accordion and the concertina...

. A person who plays the accordion is called an accordionist.

It is played by compressing or expanding the bellows whilst pressing buttons or keys

Musical keyboard

A musical keyboard is the set of adjacent depressible levers or keys on a musical instrument, particularly the piano. Keyboards typically contain keys for playing the twelve notes of the Western musical scale, with a combination of larger, longer keys and smaller, shorter keys that repeats at the...

, causing valve

Valve

A valve is a device that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but are usually discussed as a separate category...

s, called pallets, to open, which allow air to flow across strips of brass or steel, called reeds

Reed (instrument)

A reed is a thin strip of material which vibrates to produce a sound on a musical instrument. The reeds of most Woodwind instruments are made from Arundo donax or synthetic material; tuned reeds are made of metal or synthetics.-Single reeds:Single reeds are used on the mouthpieces of clarinets...

, that vibrate to produce sound inside the body.For the accordion's place among the families of musical instruments, see Henry Doktorski's Taxonomy of Musical Instruments (The Classical Free-Reed, Inc.) Also on this page is Diarmuid Pigott's The Free-Reed Family of Aerophones

The instrument is sometimes considered a one-man-band as it needs no accompanying instrument.