Cantus Firmus

Cantus firmus, Latin for "fixed song," refers to a pre-existing melody used as the foundation for a piece of music, particularly in medieval and Renaissance compositions. Composers would create complex harmonies and additional voices around this melody, allowing it to stand out while other musical lines intertwined with it. This technique helped establish a structure in sacred music, such as masses and motets, and was a key element in the development of polyphony, where multiple independent melodies convey depth and richness to the overall sound.