A diatonic accordion is a type of free-reed instrument that produces sound when air flows over reeds, which vibrate to create musical notes. Unlike chromatic accordions, diatonic accordions are designed to play in specific keys and typically have a limited number of notes. They are often used in folk music traditions around the world, including Cajun, Irish, and Polka music. These accordions feature buttons on the right side for melody and bass buttons on the left side for accompaniment. The diatonic nature means that pressing a button produces different notes when pushing or pulling the bellows, adding a unique character to the music.