A musical instrument (portable wind instrument), similar to the accordion
Like the accordion, it is a poliphonic reed instrument. Unlike the accordion, it is most often round or octagonal in shape. Its birth is sometimes traced back to Heinrich Band (born in Krefeld, Germany, on April 4, 1821) who described a very similar instrument in 1850. At the time, the bandoneon (or something similar) was sometimes referred to as "concertina".
The bandoneon is most often encountered in Argentinian music, and particularly, tango. It has achieved worldwide recognition mostly thanks to the famous tango player Astor Piazzolla