Catalan is the Romance language spoken in the coastal region of northeast Spain in the which Barcelona is the principal city. It is said to have more similarity to the Provençal language spoken across the border in France. Catalonia was once an independent kingdom with an extensive trading network in the western Mediterranean. There is a Catalan-speaking enclave on the northwest coast of Sardinia around the city of Alghero.

Within the Catalan-speaking area there is some variation as shown below.

Catalan and Portuguese differ linguistically from Castilian in that both are linguistically more conservative than Castilian. The difference in the written languages seems greater than it is verbally because of different spelling conventions in representing the spoken languages. The table below shows a comparison of the different ways the same sounds are depicted in Castilian, Portuguese and Catalan spelling.