How did Francesco Landini contribute to 14th-century Italian music?

Francesco Landini was a preeminent composer of 14th-century Italy, celebrated for his virtuosity on the organetto and his skill in improvisation. His contributions to the music of the Italian Trecento include:1

• Compositional Output: Landini was a prolific composer, leaving behind approximately 140 ballate, as well as 12 madrigals, a virelay, and a caccia. His works are noted for their stylized elegance, limpid texture, and highly ornamental, vocal-style melodies.1
• The Landini Cadence: He is the namesake of the Landini cadence, a distinctive melodic formula common in 14th-century music where the leading tone drops to the sixth of the scale before resolving to the final tonic note.1
• Secular Music: As a leading figure in the Italian school of the 14th century, his work helped define the era's secular music, which often featured a highly singable top melody supported by a lower voice. His compositions, along with those of his contemporaries, are preserved in the Squarcialupi Codex.23