Which musical form is considered the most important in medieval polyphony?

The most important musical form in medieval polyphony is the motet. This form developed as composers began to create works that featured multiple melodies sung simultaneously, with a focus on sacred texts. The motet typically involved the use of a plainchant melody as a structural basis while adding additional voices with their own distinct texts, leading to an increasing complexity in both musical texture and thematic content.

During the medieval period, the motet represented a significant advancement in the artistry and expressiveness of polyphonic music, allowing for more elaborate vocal arrangements and greater emotional depth. Its evolution marked a shift from earlier forms such as organum, which primarily involved adding one or more voices to a single chant melody, to more intricate structures that diversified the roles of individual voices.