Rondeau (forme fixe) in the context of "Chanson"

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. These examples use a multi-couplet rondo or "chain rondo" (ABACAD) known as the Italian rondo. Rondo form, also known in English by its French spelling rondeau, should not be confused with the unrelated but similarly-named forme fixe rondeau, a 14th- and 15th-century French poetic and chanson form.

A virelai is a form of medieval French verse used often in poetry and music. It is one of the three formes fixes (the others were the ballade and the rondeau) and was one of the most common verse forms set to music in Europe from the late thirteenth to the fifteenth centuries.

One of the most famous composers of virelai is Guillaume de Machaut (c. 1300–1377), who also wrote his own verse; 33 separate compositions in the form survive by him. Other composers of virelai include Jehannot de l'Escurel, one of the earliest (d. 1304), and Guillaume Dufay (c. 1400–1474), one of the latest.

The ballade (/bəˈlɑːd/; French: [balad]; not to be confused with the ballad) is a form of medieval and Renaissance French poetry as well as the corresponding musical chanson form. It was one of the three formes fixes (the other two were the rondeau and the virelai) and one of the verse forms in France most commonly set to music between the late 13th and the 15th centuries.

The formes fixes were standard forms in French-texted song of the fourteenth and fifteenth centuries. The ballade is usually in three stanzas, each ending with a refrain (a repeated segment of text and music).

Jehan de Lescurel (fl. early 14th century; also Jehannot de l'Escurel) was a composer-poet of late medieval music. Jehan's extensive surviving oeuvre is an important and rare examples of the formes fixes before the time of Guillaume de Machaut; it consists of 34 works: 20 ballades, 12 rondeaus and two long narrative poems, diz entés. All but one of his compositions is monophonic, representing the end of the trouvère tradition and the beginning of the polyphonic ars nova style centered around the formes fixes.

The Chantilly Codex (Chantilly, Musée Condé MS 564) is a manuscript of medieval music containing pieces from the style known as the Ars subtilior. It is held in the museum at the Château de Chantilly in Chantilly, Oise.

Most of the compositions in the Chantilly Codex date from c. 1350–1400. There are 112 pieces total, mostly by French composers, and all of them polyphonic. The codex contains examples of many of the most popular courtly dance styles of its time, such as ballades, rondeaus, virelais, and isorhythmic motets. Some of the motets are rhythmically extremely complex, and are written in intricately exact musical notation. Two pieces by Baude Cordier were added at a slightly later date at the front of the manuscript, and use unusual shapes to reflect their musical contents. The piece "Belle, Bonne, Sage, Plaisant" (image right) was written to a special lady for the New Year, and reflects the shape of the notation with the text (Lovely, good, wise, and pleasant). The graphic layout of the notation is a play on words on the "Cor" ("heart") in "Cordier".

The French composer Guillaume de Machaut was the most prolific composer of his time, with surviving works encompassing many forms, the three formes fixes rondeaux, virelais, ballades, as well as motets, lais and a single representative of the complainte, chanson royale, double hocket and mass genres. Most of his extant output is secular music, a notable exception being the renowned Messe de Nostre Dame. His oeuvre as a whole represents an unprecedented volume of surviving music for a single medieval composer, largely in part due to his own efforts to preserve and curate manuscripts for his music. The dominant figure of the ars nova style in late medieval music, Machaut is regarded as the most significant French composer and poet of the 14th century and often seen as the century's leading European composer.

Since many titles are merely the first lines of the texts used, in different sources individual pieces may be referred to by slightly different titles. For example, R20 is known both as Douce dame and Douce dame tant qui vivray. Furthermore, some of Machaut's works (most notably the motets) employ simultaneous performance of several different texts. In such cases, the title of the work lists all texts used, starting from the top voice.