Rondo (or rondeau) is the name of a musical form in which a principal theme or section is repeated a certain amount of times, alternating with one of more different sections (called 'digressions' or 'episodes'). The most usual formal plans for the Classical-Romantic rondo are ABA, ABACA, or ABACABA, with the main element sometimes appearing in an embellished version upon its repetition. In this way the rondeau is very similar to the ritornello form, with the difference that in the latter the main theme may appear transposed and fragmented, while in a rondo the theme is brought back in its original key and form.