Langue D'oïl refers to a group of Romance dialects historically spoken in northern France. It is one of the two main branches of the Old French language, the other being Langue d'Oc, which was spoken in the south. The term "d'oïl" comes from the word for "yes" in these dialects, distinguishing it from the southern dialects. These dialects played a significant role in the development of the French language as we know it today. Over time, Langue D'oïl evolved and contributed to the standardization of modern French, particularly during the Middle Ages when literature and administration began to favor a unified language.