Spanish, like other Romance languages in Europe, was born from the ruins of Latin, an Indo-European language that the Roman Empire expanded in the ancient world. The arrival of Latin to Hispania, in the year 218 B.C., moved away the local languages of the iberos, celts, or lusitans and was used increasingly. Nevertheless, after the weakening, fragmentation and fall of the Roman Empire of the West, the Latin language followed its own way, in which the traditional ways of expression and the new linguistic habits developed by these speakers thanks to the migratory flows came together. From 9th to 12th century, new forms of expression called "romances" emerged followed later by the peninsular Romance languages: Leonese, Castilian, Galaic-Portuguese, Navarrese-Aragonese, Catalan and Mozarabic arose independent from its mother, and each one had its own system, being Castilian the language destined to be one of the most spoken anywhere in the world.

In 1492, when Christopher Columbus arrived at America, the Castilian language was consolidated in the peninsula, but during the 15th and the 16th centuries, a true revolution in the speech took place and a new variety was born. It arrived at the New World.
generally known as the Spanish of America. In this continent, the language became richer with the contribution of the native languages of the Hispanic-American territories and began the expansion that continues nowadays.

Castilian, Romanesque dialect arisen in Castile and origin of the Spanish language, was born in the mountainous strip of the Cantabrian sea (North peninsular). The place was poorly romanized, and it had strong pre-roman roots, in which Spanish counties and medieval kingdoms arose later. New dialectal varieties of Latin were developed around those centres. Castilian was the dialect of the highlanders who defend the eastern borders of the "asturleonés" kingdom from the Arabs. The term "castilian" takes its name of Latin "castella". In the visigothic period, it meant military camp (the diminutive of castrum) and later on "land of castles". The Navarrese-Aragonese idiomatic modality, used in the place in where three kingdoms, Castile, Navarre and Aragón crossed gave origin, in the 11th century, to the first peninsular documents in a Romance language: "glosas emilianenses", written in the Monastery of Yuso (San Millán de la Cogolla). In 1042, on the other hand, the "jarchas" were written. These were the first texts in properly Castilian, but with Arab and Hebrew characters.

With the monarchic union of Castile and Aragon, the process of reconquest of the Iberian territories from the Muslims concluded with the recovery of the kingdom of Granada. In addition to this, the expulsion of the Jews in 1492, which spoke a variety of Castilian: Jewish-Spanish or Sephardi, was proposed. According to the specialists, Castilian language acted like a wedge that broke with the old unit of certain romanic common characters before extended over the peninsula. It penetrated until Andalusia, it divided some original dialectal uniformity, it broke the primitive linguistic characters from Duero river to Gibraltar, erasing the mozarabic dialects and more and more it widened his action from the north to the south to implant the linguistic special modality born in the Cantabrian corner. Simultaneously, Castilian became rich thanks to the peninsular regionalisms; for example, of Gallego and Portuguese, Leonese, Andalusian, etcetera. Thus, the Castilian unified quickly to great part of the peninsula erasing the Leonese and Aragonese dialects; it became the own romance language of Navarre, and unique language of Castile, Andalusia and the reconquered kingdom of Granada. It had such force that was not only consolidated like the language of the union, but also it saw itself definitively consecrated with the appearance of the first grammar of a Romance language: the "Grammar of the Castilian language" by Elio Antonio de Nebrija, published in 1492 and, twenty-five years later, in 1517, with the work of the same author, the "Rules of Castilian spelling", that summarizes the previous text in its orthographic part.