About AccordionAccordions (from 19th-century German Akkordeon, from Akkord—"musical chord, concord of sounds") are a family of box-shaped musical instruments of the bellows-driven free-reed aerophone type, colloquially referred to as a squeezebox. A person who plays the accordion is called an accordionist. The concertina and bandoneón are related; the harmonium and American reed organ are in the same family. The instrument is played by compressing or expanding the bellows while pressing buttons or keys, causing pallets to open, which allow air to flow across strips of brass or steel, called reeds. These vibrate to produce sound inside the body.