How is Catalan related to Occitan and Spanish?

Catalan is a Romance language that maintains distinct characteristics while sharing historical and linguistic ties with both Occitan and Spanish.1

Relationship to Occitan

Catalan is most closely related to the Occitan language of southern France. While Catalan is considered a branch of peninsular rather than southern Gallo-Romance, it shows clear kinship with Provençal. Historically, early Catalan literature relied on the Occitan language (langue d’oc) and the poetic forms of troubadours from north of the Pyrenees. Today, Catalan differs from Occitan through specific vowel sounds, diphthongs, and grammatical conventions.12

Relationship to Spanish

Though Catalan shares a common ancestry with Spanish, it is clearly distinct from it. Key differences include:1
* Diphthongs: Catalan lacks the rising diphthongs found in Spanish (e.g., ie, ue) and instead features an abundance of falling diphthongs (e.g., eu, au, ou).1
* Consonants: Catalan retains specific sounds—such as the j (as in azure), z, tj, tz, and x (as in sh)—that do not exist in modern Spanish.1
* Verb Stress: Catalan often stresses verbs on the root, whereas Spanish typically stresses the infinitive ending.1