Old French (franceis, françois, romanz; Modern French ancien français) was the Romance dialect continuum spoken in territories that span roughly the northern half of modern France and parts of modern Belgium and Switzerland from the 9th century to the 14th century. It was then known as the langue d'oïl (oïl language) to distinguish it from the langue d'oc (Occitan language, also then called Provençal), whose territory bordered that of Old French to the south. The Norman dialect was also spread to England, Ireland, the Kingdom of Sicily and the Principality of Antioch in the Levant.

Gaulish, maybe the only survivor of the continental Celtic languages in Roman times, slowly became extinct during the long centuries of Roman dominion. Only several dozen words (perhaps 200, if we add Gaulish etymology) survive in modern French, for example chêne, ‘oak tree’ and charrue ‘plough'; Delamarre (2003, pp. 389–90) lists 167.

Despite attempts to explain some phonetic changes by the action of a Gaulish substratum, only one of them is sure, because this fact is clearly attested in the Gaulish language epigraphy, e.g. : on the potteries of la Graufesenque (1st c. AD), there is the Latin word (from Greek) written paraxsid-i instead of paropsid-es. The spellings /ps/ and /pt/ are confused with /xs/ and /xt/, e.g. : Latin capsa > *kaxsa > caisse (compare Italian cassa) or captīvus > *kaxtivus > OF chaitif (Modern French chétif, compare Irish cacht 'servant' ≠ Italian cattiv-ita, Spanish cautivo). This phonetic evolution is parallel to the shift of the Latin group /kt/ in Old French (Latin factum > fait, Italian fatto, Spanish hecho or lactem* > lait ; Italian latte, Spanish leche).

French Canadian or Francophone Canadian (also Canadien in Canadian English or in French) generally refers to the descendents of French colonists who arrived in New France (Canada) in the 17th and 18th centuries. Today, French Canadians constitute the main French-speaking population of Canada.

During the mid-18th century, Canadian colonists born in French Canada expanded across North America and colonized various regions, cities, and towns. Today, the majority of French Canadians live across North America, including the United States and Canada. The province of Quebec has the largest population of French Canadian descent, although smaller communities of French Canadians exist throughout Canada and in the American region of New England, where between 1840 and 1930, roughly 900,000 French Canadians emigrated to the United States and New England, in particular.

Other terms for French Canadians that continue to reside in the province of Quebec, are Quebeckers or Québécois. French Canadians constitute the second largest ethnic group in Canada, after English Canadians and before Scottish Canadians and Irish Canadians.