The Spanish language, also known as Castilian or castellano, is spoken by around 350 million people natively, making it not only the most spoken Romance language, but the second most spoken language in the world in terms of native speakers. This rivals all but Chinese in sheer number.

21 nations use Spanish as their primary language, and it is one of six official languages of the United Nations. It is the official language of Spain, most Latin American countries (with the notable exception of Brazil) and Equatorial Guinea.

Bilingual fluency in Spanish and English is particularly useful in the United States, where its cultural and political influence is well-established and steadily growing. To a lesser extent, this is also the case with Spanish and Portuguese in Brazil.

The "regulation" of intricacy and variety in the Spanish language is undertaken by The Association of Spanish Language Academies, an organization including members from the Pacific Ocean across the Americas to Europe.