During the Middle Ages there were a number of pronunciation changes to the Spanish language including variations in the “s”, “z” and “th” range of sounds. The characteristic lisping “th” sound which is now represented in written Spanish by the letter “z” and the letter “c” when it appears before an “e” or an “i” became standard in most parts of Spain, apart from Andalucía, the Canary Islands and by extension throughout South America. There is a legend that the lisped “th” was widely adopted in imitation of a Spanish king who had a speech impediment. Although this story is very popular and oft-repeated, it has absolutely no historical basis.
Other changes which differentiated Spanish from its Latin roots were the softening of certain consonant sounds, e.g. Latin “vita” to Spanish “vida” (life), Latin “lupus” to Spanish “lobo” (wolf); the introduction of diphthongs (double vowel sounds) e.g. Latin “terra” to Spanish “tierra” (earth), Latin “novum” to Spanish “nuevo” (new) and the creation of the “ñ” sound from the Latin “nn” e.g. Latin “annum” to Spanish “año”.
The process of re-conquering Spain from the Moorish kingdoms drew to a close in the late 15th century with the fall of Granada. This occurred shortly after the kingdoms of Castilla and Aragón had reached a form of political union by the marriage of their monarchs Isabel of Castilla and Fernando of Aragón. This same period saw the expulsion of the Jews and the discovery of America and so marked the beginning of what is regarded in historical terms as the foundation of modern Spain. At this time the very first Castilian Grammar book was published by Antonio de Nebrija in Salamanca in which Spanish was studied as a modern language as distinct from Latin.
With the expansion of the Spanish Empire, Castilian became the official language of the colonies of modern Central America, Peru, Colombia, Uruguay, the Philippines, Guam and other Pacific islands. In the late 18th century Spain renounced its rights to large areas of North America although Spanish place names still remain (Las Vegas, Los Angeles). On gaining independence, the former Spanish colonies of Central and South America established Spanish as their official languages whilst many southern states of North America (Florida, Texas, Arizona, California, Colorado, Nevada, New Mexico and Utah) remained predominantly Spanish speaking, despite their official language being English.
Nowadays, it is calculated that there are around 468 million native Spanish speakers worldwide, with an additional 90 million second language speakers and students of the Spanish language. In fact, Spanish is the second most widely spoken native language in the world, after Chinese and before English, although English has many more second language and foreign language speakers.