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

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.

A lai (or lay lyrique, "lyric lay", to distinguish it from a lai breton) is a lyrical, narrative poem written in octosyllabic couplets that often deals with tales of adventure and romance. Lais were mainly composed in France and Germany, during the 13th and 14th centuries. The English term lay is a 13th-century loan from Old French lai. The origin of the French term itself is unclear; perhaps it is itself a loan from German Leich (reflected in archaic or dialectal English lake, "sport, play" and in modern Swedish (att leka = to play). The terms note, nota and notula (as used by Johannes de Grocheio) appear to have been synonyms for lai.

The poetic form of the lai usually has several stanzas, none of which have the same form. As a result, the accompanying music consists of sections which do not repeat. This distinguishes the lai from other common types of musically important verse of the period (for example, the rondeau and the ballade). Towards the end of its development in the 14th century, some lais repeat stanzas, but usually only in the longer examples. There is one very late example of a lai, written to mourn the defeat of the French at the Battle of Agincourt (1415), (Lay de la guerre, by Pierre de Nesson) but no music for it survives.

The formes fixes (French: [fɔʁm fiks]; singular: forme fixe, "fixed form") are the three 14th- and 15th-century French poetic forms: the ballade, rondeau, and virelai. Each was also a musical form, generally a chanson, and all consisted of a complex pattern of repetition of verses and a refrain with musical content in two main sections.

All three forms can be found in 13th-century sources, but a 15th-century source gives Philippe de Vitry as their first composer while the first comprehensive repertory of these forms was written by Guillaume de Machaut. The formes fixes stopped being used in music around the end of the 15th century, although their influence continued (in poetry they, especially the rondeau, continued to be used).

A rondeau (French: [ʁɔ̃do]; plural: rondeaux) is a form of medieval and Renaissance French poetry, as well as the corresponding musical chanson form. Together with the ballade and the virelai it was considered one of three formes fixes, and one of the verse forms in France most commonly set to music between the late 13th and the 15th centuries. It is structured around a fixed pattern of repetition of verse with a refrain. The rondeau is believed to have originated in dance songs involving singing of the refrain by a group alternating with the other lines by a soloist. The term "Rondeau" is used both in a wider sense, covering older styles of the form which are sometimes distinguished as the triolet and rondel, and in a narrower sense referring to a 15-line style which developed from these forms in the 15th and 16th centuries. The rondeau is unrelated to the much later instrumental dance form that shares the same name in French baroque music, which is more commonly called the rondo form in classical 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.