Guillaume de Machaut was a French composer and poet who was the central figure of the ars nova style in late medieval music. His dominance of the genre is such that modern musicologists use his death to separate the ars nova from the subsequent ars subtilior movement. Regarded as the most significant French composer and poet of the 14th century, he is often seen as the century's leading European composer.

Ars nova refers to a musical style which flourished in the Kingdom of France and its surroundings during the Late Middle Ages. More particularly, it refers to the period between the preparation of the Roman de Fauvel (1310s) and the death of composer Guillaume de Machaut in 1377. The term is sometimes used more generally to refer to all European polyphonic music of the fourteenth century. For instance, the term "Italian ars nova" is sometimes used to denote the music of Francesco Landini and his compatriots, although Trecento music is the more common term for the contemporary 14th-century music in Italy. The "ars" in "ars nova" can be read as "technique", or "style". The term was first used in two musical treatises, titled Ars novae musicae by Johannes de Muris, and a collection of writings attributed to Philippe de Vitry often simply called "Ars nova" today. Musicologist Johannes Wolf first applied to the term as description of an entire era in 1904.