Spanish or Castilian is a Romance language originally from the northern area of Spain. It is the official language of Spain, most Latin American countries and one of the official languages of Equatorial Guinea, in Africa. In total, twenty-five nations and territories use Spanish as their primary language. In addition, it is an important language in many others.

Spanish originated as a Latin dialect along the remote cross road strips among the Cantabria, Burgos, Soria and La Rioja provinces of Northern Spain. From there, its use gradually spread inside the  Kingdom of Castile, where it evolved and eventually became the principal language of the government and trade. It was later brought to the Americas and other parts of the world in the last five centuries by Spanish explorers and colonists.

The language is spoken by between 322 and 400 million people natively, making Spanish the most spoken Romance language and possibly the second most spoken language by number of native speakers. It is estimated that the combined total of native and non-native Spanish speakers is approximately 500 million, probably making it the fourth most spoken language by total number of speakers.

It is one of six official working languages of the United Nations. The language is spoken most extensively in the Americas, Spain and to a small extent in Africa and Asia Pacific. It is also the second most widely spoken language in the United States and by far the most popular studied foreign language in U.S. schools and Universities. Within the globalized market, there is currently an international expansion and recognition of the Spanish language in literature, the film industry, television and music.