Musical pieces are compositions written for performance by musicians. Rondos (6 letters) are a type of musical form that consists of a main theme that is repeated throughout the piece, with variations and episodes in between. Sonatas (7 letters) are multi-movement works for solo instruments or small ensembles. Etudes (6 letters) are short pieces composed to help musicians practice and develop their technique. DUOS (4 letters) are compositions for two performers, while duets (5 letters) are compositions for two performers playing the same instrument. Opuses (6 letters) are works of art, usually musical compositions, that are numbered to indicate the order of the artist's work.