The mouth organ, commonly known as the harmonica, is a small, portable musical instrument played by drawing air through reeds. These reeds vibrate to produce sound, and the instrument typically has multiple holes, each corresponding to different notes. The harmonica is popular in various music genres, including blues, folk, and rock. Made from metal, plastic, or wood, the harmonica comes in different types, such as diatonic, chromatic, and tremolo. It is often used for solo performances or as an accompaniment to other instruments. Its compact size makes it easy to carry, allowing musicians to play it anywhere.