The standard for French is based on the dialect of Île de France (technically known as Francien) which has been the official standard language since the mid-16th century. Francien has largely replaced other regional dialects of French spoken in northern and central France; these dialects made up the so-called Langue d’oïl (the term is based on the French use of the word oïl, modern oui, for yes). French dialects are classified in 5 groups:
- Central: Francien, Orléanais, Bourbonnais, Champenois;
- Northern: Picard, Northern Norman, Walloon (usually considered a separate language);
- Eastern: Lorrain, Bourguignon (Burgundian), Franc-Comtois;
- Western: Norman, Gallo (around the Celtic Breton area), Angevin, Maine;
- Southwestern: Poitevin, Saintongeais, Angoumois.
Regional dialects of French survive for the most part only in uneducated rural speech, although the Picard-Walloon dialect of northern France and the Norman dialect of western France gave strong competition to Francien in medieval times, and Walloon is still spoken in Belgium.
The French language of Canada, originally probably of northwestern dialect type, has developed a lot of individual features. There exist also many French-based creoles (in Haiti, USA, the Carribbean islands etc.).
Standard French has also greatly reduced the use of the Occitan language of southern France (the so-called Langue d’oc, from Provençal oc for yes). Occitan’s major dialect, Provençal, was a widely used medieval literary language.