The Spanish language was carried by Spanish colonists to the Canary Islands, the Antilles, the Philippines, southern North America, the greater part of South America, and the coast of Africa. In the Iberian peninsula the Spanish-language area does not coincide exactly with the political boundaries of Spain. Spain contains three non-Spanish-speaking regions: Galicia, in the north-west, where Gallegan (technically a dialect of Portuguese) is spoken; the Basque provinces, in the north, where Basque, a unique agglutinative language, is spoken; and Catalonia, along the east coast, where Catalan, also a Romance language, is spoken. Catalan is also spoken in the Balearic Islands; in France, in the Pyrénées-Orientales; and in parts of Cuba and Argentina. 

In its grammatical structure Castilian Spanish is generally in conformity with French, Italian, Portuguese, and the other Romance languages.

Spanish is a Romance language, meaning that it is a vernacular descendant of Latin, the official language of the Roman Empire and a branch of the Indo-European. In addition to Spanish, the Romance group includes such national languages as Portuguese, French, Italian, and Rumanian, as well as regional languages and dialects like Catalan, Galician, Occitan, Rheto-Romance and Sardinian.

Like the other Romance languages, Spanish is derived from Vulgar Latin, the cluster of dialects spoken by legionaries, traders, farmers and the like. Vulgar Latin was presumably always subject to considerable geographical variation, although not to the extent of becoming unintelligible by Latin speakers from different parts of the Roman Empire.

Regional varieties gradually drifted apart, a process that can only have accelerated after the Western Empire collapsed in the 5th century and the old Roman provinces were overrun by Germanic tribes.

There are, then, no precise moments when the modern Romance languages were born. In the case of Spanish texts from the Castile area (the county the languages came from) begin to exhibit Romance features from the 10th century onwards, but the 12th century texts are the first that have a clear Spanish look. As ever, though, writing would have lagged behind speech, especially as for centuries an established orthography existed for Latin but not for the emerging Romance vernaculars.

Spanish has its roots in the rustic Latin of southern Cantabria and has grown from an obscure provincial dialect to the rise of Castile kingdom. Initially a small enclave on the eastern edge of the kingdom of León, Castile played a leading role in the Reconquest (after Islamic occupation), expanded progressively southwards and, by the 14th century, controlled all of the Peninsula except Portugal, Navarre, Aragon and the surviving Muslim kingdom of Granada.

With the unification of Castile and Aragon in 1479 by the Catholic Kings, the modern Spanish nation-state was born and shortly afterwards Columbus's discovery of America initiated a new colonial phase. In this way, the language of Castile came to dominate not just in the Peninsula (with the notable exceptions of Portugal, Galicia, the Basque Country and Catalonia) but, from the 16th century onwards, in the American colonies too. The year of 1611 saw the publication of the first Spanish dictionary, by Sebastian de Covarrubias.

An influx of new words
Spanish became the major diplomatic language until the eighteenth century. The lexicon at this time began to incorporate a large body of words from other languages, both European and Native American.  From Italian came such new words as: "soneto", "medalla" and "piano". Gallicisms included: "jardín" and "sargento". Words like "patata", "cóndor", "alpaca" and "puma" came from Quechua and Guarani. From the family of Nahuatl languages came such familiar vocabulary as: "chocolate", "tomate" and "cacao".

Spanish Today
In 1713, the Real Academia Española was founded. It established authoritative criteria for the sanctioning of neologisms and the incorporation of international words. Spanish grammar was formalised during this period and there was a great flourish in Hispanic literature, helped by Spanish's relatively free word order, creating a variety of diverse literary styles.

The twentieth century has seen further alterations in how Spanish is used by its speakers. The eruption of neologisms, fuelled by technological and scientific advances, remains unabated. They range from the classic: "termómetro", "átomo" and "psicoanálisis" to the most modern and barely hispanicised: "filmar", "radar", "casete", "PC" and "módem".

The Vulgar Latin spoken by Roman armies and settlers in ancient Spain formed the basis of the many Spanish dialects that developed in the various regions of the country during the Middle Ages. The dialect of Castile, or Castilian Spanish, gradually became the accepted standard as Castile gained political dominance in the 13th century.

While the majority of Spanish words derive from Latin, many are taken from other sources; for example, pre-Latin languages such as Greek, Basque, and Celtic. The invasion of the Visigoths early in the 5th century AD introduced a few Germanic words. The Muslim conquest three centuries later brought in a large number of Arabic words, many of which are easily detected by the prefixed Arabic article al. Under the influence, beginning in the 11th century, of French ecclesiastics and pilgrims on their way to Santiago de Compostela in north-western Spain, the Spanish vocabulary was appreciably augmented by words and phrases from French. During the 15th and 16th centuries an infusion of elements from the Italian occurred because of Aragonese domination in Italy and the great vogue of Italian poetry in Spain. Relations between Spain and its colonies and possessions have led to the introduction of terms from Native American languages and other sources, and scholarly activities have constantly increased the stock of borrowed words.