A kazoo is a simple musical instrument that produces sound when a person hums into it. It is typically made of metal, plastic, or wood and has a small, hollow body with a membrane that vibrates to create a buzzing sound. Kazoos are often used in children's music, folk songs, and informal gatherings due to their ease of use and playful sound. The kazoo is believed to have originated in the early 19th century and is related to other instruments like the mouth harp and jew's harp. It is popular in various music genres, including blues and jug band music, and is often used for fun and entertainment.