Franchinus Gaffurius (c. 1451–1522) was an influential Italian music theorist, composer, and organist of the Renaissance period. He is best known for his contributions to the development of music theory, particularly in the realm of counterpoint and harmony. Gaffurius served as the maestro di cappella at the Milan Cathedral, where his work significantly impacted the musical practices of the time. His notable theoretical works include "Theorica musicae" (1492) and "Pratica musicae" (1518), which explored the principles of music theory, notation, and the relationship between music and mathematics. Gaffurius's writings were vital in bridging the gap between the medieval and Renaissance approaches to music, emphasizing the importance of both practical musicianship and theoretical knowledge. In addition to his theoretical contributions, Gaffurius composed various sacred choral works, which reflected the polyphonic styles emerging during the Renaissance. His impact on music can be seen in the way his theories influenced later composers and theorists, helping to shape the evolution of Western music. Gaffurius remains a notable figure for his role in establishing foundational concepts in music theory that are still relevant today.