Spanish is a Romance language spoken throughout the world by more than 400 million people — over 350 million of them as native speakers. Depending on the reckoning, it is between the 2nd and 4th most spoken language on Earth, and it is without a doubt the most spoken of the Romance languages. In Spanish, the term for the language is either español or castellano, depending on the area in question. In English, the term Castilian is also sometimes used to refer to the language, but this usage is much less common. Castilian may also be used as a term to describe the dialect spoken in the Castile region of Spain.
This language is mutually intelligible with a number of other Iberian Romance languages, most notably Portuguese. In general, a Portuguese speaker will have an easier time understanding Spanish than will a Spanish speaker listening to Portuguese, but for both, comprehension should be possible. To non-speakers, the languages often sound like the same tongue — perhaps just different dialects — but the differences are readily apparent upon closer examination. Spanish also shares enough common language with Italian — another Romance language — to allow a fair degree of inter-communication. Though by no means allowing for a free understanding or speaking of the other tongue, many Spanish speakers find that if an Italian speaker talks slowly enough and avoids slang, most of the content of speech can be pieced together.
Like the other popular Romance languages — Portuguese, French, and Italian — most English speakers find Spanish is relatively easy to learn. English itself draws on enough Latin vocabulary and grammar that Spanish is littered with cognates that aid in early language acquisition. The sounds used are also fairly familiar to English speakers — with the possible exception of the rolled and tapped ‘r’ sounds — so there is a surmountable learning curve in pronunciation.
Spanish is an official language of the majority of countries in Central and South America, including Argentina, Columbia, El Salvador, Mexico, Nicaragua, Peru, Uruguay, and Venezuela. It is also the official language of the island nations of Cuba, the Dominican Republic, and Puerto Rico. It is an operating language of both the European Union and the United Nations. The language is widely spoken in the United States and is an official language in the state of New Mexico. Alongside Arabic, it is one of the official languages of the African nation of Western Sahara. It is, of course, also one of the official languages of Spain.
As a language, Spanish is a major force in the United States, where it is spoken by more than 30 million people, making the United States the fifth ranking nation of speakers of this language, behind only Argentina, Spain, Columbia, and Mexico. Because of the steady immigration between countries where it is spoken and the United States, the language has a steady place in the culture of the US, and many non-native speakers find learning the language extremely helpful in business and social situations.