The bandoneon is a type of concertina, a musical instrument that belongs to the free-reed family. It originated in Germany in the 19th century and was later popularized in Argentina, where it became a key instrument in tango music. The bandoneon has a distinctive sound, produced by air flowing through metal reeds when the bellows are pushed and pulled. Typically, the bandoneon has buttons on both ends, allowing for a wide range of notes and chords. It is often played in ensembles or orchestras, contributing to the rich, emotional sound characteristic of tango. Notable composers and musicians, such as Astor Piazzolla, have helped elevate the bandoneon to a prominent place in both traditional and contemporary music.