How did medieval songs use stanzas, rhyme, and refrains?

In medieval vocal music, the organization of texts into stanzas, rhymes, and metrical patterns was largely inherited from earlier medieval Latin traditions. These structural elements were essential for unifying poetic form and creating rhythmic consistency in secular songs, such as those composed by the troubadours and trouvères.1

• Stanzas and Rhyme: Poets utilized strophic designs where texts were organized into regular stanzas. Rhyme schemes were employed to unify these sections, often using end rhyme to echo final syllables. While early medieval verse sometimes relied on assonance, end rhyme became increasingly dominant by the 13th century.12
• Refrains: To these established structures, the trouvères added the refrain—a recurring phrase or line of varying length placed within or between stanzas.1
• Fixed Forms: Over time, these elements coalesced into "fixed forms" with specific patterns of repetition, such as the ballade, rondeau, and virelai, where capital letters in diagrams typically denote the placement of the refrain.1