The accordion is widely spread across the world because of the waves of immigration from Europe to the Americas and other regions. The performer normally plays the melody on buttons or keys on the right-hand side (referred to as the manual), and the accompaniment on bass or pre-set chord buttons on the left-hand side. Valves on opposing reeds of each note are used to make the instrument's reeds sound louder without air leaking from each reed block. These vibrate to produce sound inside the body. The accordion 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. The harmonium and American reed organ are in the same family, but are typically larger than an accordion and sit on a surface or the floor. The concertina and bandoneĆ³n are related.
A person who plays the accordion is an accordionist. Accordions (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 ( producing sound as air flows past a reed in a frame), colloquially referred to as a squeezebox.