Occitan is  romance language, that is the result of the evolution of spoken latin after the fall of the roman empire,like french, spanish, italian, portuguese, catalan,
romanian and rhetian. This evolution has been widely influenced by the languages spoken before the arrival of the romans, i.e. celtic Gallic in the northern part of Occitania and Iberic Aquitan (probably the languange of the Basques' ancestors) in the southwestern part. Then the evolutions have spread over the domain and the differences have slightly been smoothed. This entails that occitan is an intermediary step between iberic tongues on the one hand (like Castillan or Portuguese) and French on the other hand, which has undergone deep changes after the germanic invasions in the IVth-VIth century. It must be added that occitan is very similar to Catalan and in fact, many scientists think occitan and Catalan should be regarded as different dialects of the same Catalano-occitan language.

Occitània is just the collection of Occitan speaking areas, in the form of its six main dialects : Provençal, Languedocien, Gascon, Auvernhat, Limousin and Alpine. This territory has never konw any political unification, but mutual understanding between the diferent dialects, as well as a large number of cultural similarities in the fields of mentalities, cooking, architecture etc are the reason to consider it as a genuine entity..To know more about this territory, visit the Occitan countries section.
 

Main characteristics of the language : Occitan vs. French

• French changed most of Latin A latinas into [e], while Occitan retained the latin sound. Compare Latin NASUM, Occitan nas and French nez. 
• French changed many Latin O into [oe], while Occitan retained them. Compare Latin FLOREM, Occitan flor and French fleur. 
• French changed many Latin E into [wa], while Occitan retained them [e] sound. Compare Latin PERAM, Occitan pera French poire. 
• French changed the Latin AU group into [o], Latin AI into [e] and Latin EI into [wa], while Occitan retained the Latin [au], [ai] e [ei] sounds. Compare Latin AURICULAM, Occitan aurelha and French oreille, or (spoken) Latin FAITUM (for FACTUM), Occitan fait and French fait (pronounced [fè]), or (spoken) Latin DREITUM (for DIRECTUM), Occitan dreit and French droit. 
• French just suppressed many of non stressed Latin vowelswhile Occitan retained them. Compare Latin CABALLUM, Occitan caval, French cheval (the e is dropped in the pronounciation : [shfal]), Latin LUNA, Occitan luna, French lune (Again, the e is dropped  [lün]). 
• French also suppressed a lot of Latin consonants which Occitan retained. Compare Latin MATURUS, Occitan madur and French mûr, or Latin EXCADENTIA, Occitan escasença and French échéance.

Occitan is no "distorted French". French institutions, among which most of the school teaachers have spread the idea that Occitan is only a "patois", a distorted form of French. This is of course definitely wrong. Occitan and French are just two different languages which formed themselves independently out of Latin. Moreover, the differences above show that Occitan remained closer to Latin than French did. If the relationship was relevant, one should then consider French as distorted, over evoluted Occitan.

If you are interested in more details, visit the  linguistics section.