Spanish: A Romance Language from Latin's Iberian Branch

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.