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BRIEF HISTORY
The accordion is a box-shaped musical instrument of the bellows-driven free-reed aerophone family, sometimes colloquially referred to as a squeezebox. A person who plays the accordion is called an accordionist. The instrument is played by compressing or expanding the bellows whilst pressing buttons or keys, causing valves, called pallets, to open, which allow air to flow across strips of brass or steel, called reeds that vibrate to produce sound inside the body.
This instrument is sometimes considered a one-man-band, as it needs no accompanying instrument. The performer normally plays the melody on buttons or keys on the right-hand manual, and the accompaniment, consisting of bass and pre-set chord buttons, on the left-hand manual. The accordion is often used in folk music in Europe, North America and South America, and in some countries, such as Brazil and Mexico, it is also commonly used in mainstream pop music. In Europe and North-America, it is often associated with busking. Some popular music acts also make use of the instrument. Additionally, the accordion is sometimes used in both solo and orchestra performances of classical music.
The oldest name for this group of instruments is actually harmonika, from the Greek harmonikos, meaning harmonic and musical. It is believed that the first person to build the basic model of the accordion in 1822 was Friedrich Buschmann from Berlin; however it was Cyrillus Damian of Vienna who patented the name “Accordion” in 1829.

From: www.ask.com/wiki/Accordion