Languages of Catalonia
The main cause of Spanish and Catalan social bilingualism in modern Catalonia was large-scale migration from the rest of Spain during the 20th century, as Catalonia started a significant industrialization which demanded an increased workforce from elsewhere. Spanish has historically been spoken among a minority of civil servants born in other regions in Spain and among segments of the wealthiest bourgeoisie. Spanish has also been spoken as a second language by most Catalans, as it has been the only official language over long periods since the eighteenth century.
Catalan language
Western Catalan comprises the two dialects of Northwestern Catalan and Valencian; the Eastern block comprises four dialects: Central Catalan, Balearic, Rossellonese, and Alguerese. Each dialect can be further subdivided in several subdialects. The terms "Catalan" and "Valencian" (respectively used in Catalonia and the Valencian Community) are two varieties of the same language. There are two institutions regulating the two standard varieties, the Institute of Catalan Studies in Catalonia and the Valencian Academy of the Language in the Valencian Community.