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, colloquially referred to as a squeezebox. A person who plays the accordion is called an accordionist.https://en.wikipedia.org/wiki/Accordion
Types of Accordions
Each variation of the accordion can have a different design, they can be made of different material, and have a different number of keys.
They can even produce different sounding melodies. The two main types of accordion are the button accordion and the piano accordion.
Then, between these two types, there can be unisonoric and bisonoric accordions. This simply refers to how the bellows produce notes and pitches when moving air through the reeds.
Lastly, we can make distinctions between the different types of accordions based on whether they are diatonic or chromatic.
These types of accordions have black and white piano keys on the right/treble side. Piano accordions are always chromatic and unisonoric (capable of only playing one pitch per key, see below note on unisonoric accordions).
On the other hand, button accordions have buttons on the right/treble side of the accordion.
Unisonoric accordions produce the same pitch or note no matter which direction the bellow moves. However, the actual pitch can vary dependant on the size of the accordion.
These accordion types can produce two different pitches or notes depending on the direction in which the bellow moves. For example, when the bellows are pulled out, they make a completely different note compared to when they are pushed inward. Hence the “bi” in bisonoric.
These types of accordions are mostly button accordions and you can tell them apart from others because they have one to multiple rows of buttons and the reeds are bisonoric (see above).
Most diatonic button accordions are generally only in one or two keys, players need many instruments to play in various keys.
Button accordions can also be chromatic accordions. However, chromatic button accordions are unisonoric. This means that each button only plays one pitch (see above note on unisonoric accordions).
The right-hand side usually has three to five rows of buttons. These kinds of accordions are not limited to any specific key. For example, one chromatic accordion can play in many different keys. On the other hand, piano accordions are always chromatic and unisonoric.