Rondo

The rondo or rondeau is a musical form that contains a principal theme (sometimes called the "refrain") which alternates with one or more contrasting themes (generally called "episodes", but also referred to as "digressions" or "couplets"). Some possible patterns include: ABACA, ABACAB, ABACBA, or ABACABA (with the letter 'A' representing the refrain). The rondo form emerged in the Baroque period and became increasingly popular during the Classical period. The earliest examples of compositions employing rondo form are found within Italian operatic arias and choruses from the first years of the 17th century.