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.
There are four lais in the Roman de Fauvel, all of them anonymous. The lai reached its highest level of development as a musical and poetic form in the work of Guillaume de Machaut; 19 separate lais by this 14th-century ars nova composer survive, and they are among his most sophisticated and highly-developed secular compositions.
Other terms for the lai, or for forms which were very similar to the lai, include the descort (Provençal) and the leich (German).
Composers of lais
Aimeric de Peguilhan
Guilhem Augier Novella
Charles d'Anjou
Tannhäuser
Gautier de Coinci
Gautier de Dargies
Guillaume li Vinier
Adam de Givenchi
Thomas Herier
Guillaume de Machaut
Philippe de Vitry (uncertain; works attributed to him may be anonymous)
Marie de France