A button accordion is a type of accordion on which the melody-side keyboard consists of a series of buttons. This differs from the piano accordion, which has piano-style keys. Erich von Hornbostel and Curt Sachs categorize it as a free reed aerophone in their classification of instruments, published in 1914. The sound from the instrument is produced by the vibration of air in reeds. Button accordions of various types are particularly common in European countries and countries where European people settled. The button accordion is often confused with the concertina; the button accordion's buttons are on the front of the instrument, where as the concertina's are on the sides and pushed in parallel with the bellows.

A push-button or simply button is a simple switch mechanism to control some aspect of a machine or a process. Buttons are typically made out of hard material, usually plastic or metal. The surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed or pushed. Buttons are most often biased switches, although many un-biased buttons still require a spring to return to their un-pushed state.