Spanish

Spanish, also called Castilian, developed from Vulgar Latin in the Iberian Peninsula's Castile region during the medieval period, absorbing substantial vocabulary from Arabic during the centuries of Muslim Al-Andalus rule, and became Spain's dominant literary language following the Reconquista's completion and the language's codification under Alfonso X in the thirteenth century. Spanish colonial expansion from the late fifteenth century carried the language across most of Latin America, parts of the Caribbean and the Philippines, making it today the world's second most spoken language by native speakers and the official or co-official language of some twenty countries, with regional variation significant enough that Latin American Spanish and Peninsular Spanish differ noticeably in vocabulary, pronunciation and some grammar while remaining mutually intelligible.

Spanish belongs to the Romance branch of the Indo-European family alongside Portuguese, French, Italian and Romanian, all descended from Latin, and its close relationship to Portuguese in particular produces significant mutual intelligibility, especially in written form, reflecting their shared Iberian Latin origin and centuries of geographic proximity across the peninsula and the wider Iberian colonial world.

Spanish carries one of the largest bodies of Catholic devotional and missionary literature of any language, produced through Spain's role as the principal vector of Catholic Christianity into the Americas from the sixteenth century onward, including foundational catechisms, saints' lives and Marian devotional works composed for and adapted to indigenous American audiences, often alongside or in translation from Latin liturgical texts. Spanish-language Marian devotion is particularly significant given the reported 1531 apparitions of the Virgin of Guadalupe in Mexico, whose account and subsequent devotional literature, composed substantially in Spanish and Nahuatl, became foundational to Latin American Catholic identity and produced one of Catholicism's most visited pilgrimage traditions.

Spanish remains the working language of the Catholic Church across Latin America and Spain, home to the world's largest number of Spanish-speaking Catholics, and has more recently become a major language of Pentecostal and evangelical Protestant growth across Latin America and US Hispanic communities, alongside its historical association with the Spanish Inquisition's own extensive Spanish-language theological and legal literature policing religious orthodoxy for over three centuries.