Catalan is the co-official language spoken in Catalonia, in northeastern Spain. A slightly different variety is spoken in the Balearic Islands as well. Over 9 million people speak Catalan in Spain. Studying catalan at school used to be compulsory.
Valencian is the co-official language in the Valencian Community. There has been much debate on whether Valencian can be considered a language as such or a dialectal variety of Catalan. 29 % of the population in the Valencian Community speaks Valencian.
Galician is spoken in Galicia, northwestern Spain. It is the mother tongue of more than half of the population in the community of Galicia. Spanish is usually the main language in the city areas and Galician is more common in the rural ones.
Basque is spoken in the Basque country, a region of northern Spain. Unlike the other co-official languages, Basque does not come from a Romance language. In fact, its origin is unknown, as it is not related to any other European language.