The langues d'oïl are a dialect continuum that includes standard French and its closest autochthonous relatives historically spoken in the northern half of France, southern Belgium, and the Channel Islands. They belong to the larger category of Gallo-Romance languages, which also include the historical languages of east-central France and western Switzerland, southern France, portions of northern Italy, the Val d'Aran in Spain, and under certain acceptations those of Catalonia.

French is a Romance language of the Indo-European family. It descended from the Vulgar Latin of the Roman Empire, as did all Romance languages. French evolved from Gallo-Romance, the Latin spoken in Gaul, and more specifically in Northern Gaul. Its closest relatives are the other langues d'oïl—languages historically spoken in northern France and in southern Belgium, which French (Francien) largely supplanted. French was also influenced by native Celtic languages of Northern Roman Gaul like Gallia Belgica and by the (Germanic) Frankish language of the post-Roman Frankish invaders. Today, owing to the French colonial empire, there are numerous French-based creole languages, most notably Haitian Creole. A French-speaking person or nation may be referred to as Francophone in both English and French.