Names given to the Spanish language

There are two names given to the Spanish language: Spanish (español) and Castilian (castellano). Originally Castilian referred to the language of the Kingdom of Castile that spread across Spain. The original Castilian is not spoken anymore, but can be read in many texts such as "El cantar del Mio Cid". Castilian and the other languages in Hispania were modified by Latin. This fact facilitated the expansion of Castilian to the rest of the kingdom, so Latin was the 'glue' that joined the different dialects at that time. The new language had similarities with the old Castilian, but was different enough to receive a new name when it became the national language. Then, it was known virtually always as Spanish in English. That is why referring to Spanish with the term castellano is not correct, and this is why in the Real Academia's Diccionario de Lengua Española the term 'Castellano' is no longer synonymous with 'Español'.
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