Formes fixes (English: fixe forms) are French poetic forms of the fourteenth and fifteenth centuries which were translated into musical forms, particularly the forms of songs. Specifically, these forms were the ballade, rondeau, and virelai. These forms all consist of a complex pattern of repetition of verses and a refrain, with the musical content in two main sections. All three of these forms can be found in thirteenth century sources, but a fifteenth century source gives Philippe de Vitry as the first composer in these forms. The first comprehensive repertory of these forms was written by Guillaume de Machaut.