Accordions are a family of box-shaped musical instruments of the bellows-driven free reed aerophone type. The essential characteristic of the accordion is to combine in one instrument a melody section, also called the diskant, usually on the right-hand keyboard, with an accompaniment or Basso continuo functionality on the left-hand. The musician normally plays the melody on buttons or keys on the right-hand side, and the accompaniment on bass or pre-set chord buttons on the left-hand side. A person who plays the accordion is called an accordionist.

The garmon, commonly called garmoshka, is a kind of Russian button accordion, a free-reed wind instrument. A garmon has two rows of buttons on the right side, which play the notes of a diatonic scale, and at least two rows of buttons on the left side, which play the primary chords in the key of the instrument as well as its relative harmonic minor key. Many instruments have additional right-hand buttons with useful accidental notes, additional left-hand chords for playing in related keys, and a row of free-bass buttons, to facilitate playing of bass melodies.