The rondo is a musical form that contains a principal theme which alternates with one or more contrasting themes, generally called "episodes", but also occasionally referred to as "digressions" or "couplets". Some possible patterns include: ABACA, ABACAB, ABACBA, or ABACABA.

In music, an aria is a self-contained piece for one voice, with or without instrumental or orchestral accompaniment, normally part of a larger work.