A button accordion is a type of accordion on which the melody-side keyboard consists of a series of buttons rather than piano-style keys of a piano accordion. The first button accordion is credited to Franz Walther in 1850. It is a instrument very common in the south of Brazil.
The diatonic button accordion generally has two or three rows of buttons, each row tuned to a certain key. (The Cajun accordion or single-row button accordion is also a diatonic accordion.)They are usually seen in music genres such as Irish, British, Cajun, and Norteño music. Most diatonic accordions are bisonoric, meaning that a button produces two different notes by pushing or pulling the bellows. Accidentals are either not included or provided on additional "helper" buttons.
The chromatic button accordion is unisonoric, meaning that each button produces one note, whether pushing or pulling the bellows. This accordion also has 3-5 rows of buttons, but unlike the diatonic button accordion, it can be freely played in any key, usually with identical fingering patterns. This type of accordion is very popular in French music.
There are four main components of any accordion: the reeds, bellows, buttons or keys, and the switches. The accordion has reeds on both the treble and bass sides,The buttons or keys allow air into the reeds to make a sound.The bellows are considered the life of the instrument, as they expand and contract they draw air into the reeds, and are usually made out of paper. Lastly, the switches control the timbre or voice of the instrument.