Spanish (ⁱ/ˈspænɪʃ/, español), also called Castilian (ⁱ/kæˈstɪliən/,  castellano ), is a Romance language that originated in the Castile region of Spain and today has hundreds of millions of native-speakers across the world.

Spanish is a part of the Ibero-Romance group of languages, which evolved from several dialects of common Latin in Iberia after the collapse of the Western Roman Empire in the 5th century. It was first documented in central-northern Iberia in the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia. Beginning in the early 16th century, Spanish was taken to the colonies of the Spanish Empire, most notably to the Americas, as well as territories in Africa, Oceania and the Philippines.

From its beginnings, Spanish vocabulary was influenced by its contact with Basque, as well as by neighboring Ibero-Romance languages, and later it absorbed many Arabic words during the Al-Andalus era in the Iberian Peninsula. It also adopted words from non-Iberian languages, particularly the Romance languages Occitan, French, Italian and Sardinian, as well as from Nahuatl and other Indigenous languages of the Americas.