A rondo is a musical composition that is characterized by a recurring melody, known as the refrain, which alternates with contrasting episodes. The refrain is typically played at the beginning of the piece, and then returns throughout the piece, alternating with the episodes. The episodes are typically contrasting in character to the refrain, and may be in a different key or tempo. The rondo form is often used in classical music, particularly in the Classical period, and can be found in a variety of genres, including sonatas, concertos, and symphonies.