Spanish is spoken by about 400 million people around the world, which makes it the third most popular language in the world, right after English and Mandarin Chinese. While English has more speakers than any other language, most of these speakers are not native and have a different mother tongue. If that is taken into consideration, Spanish becomes the second language in the world. Besides being the official language in 21 countries, Spanish is also widely spoken in small colonies around the world.

There are numerous Spanish dialects and variations. In Spain, where several dialects are used, Castilian is taken as the national standard. Castilian is also widely used in certain Latin American countries such as Argentina, Uruguay, Paraguay, and certain areas of Ecuador. Other Latin American countries speak their own variety of Spanish, influenced by the local aboriginal languages and the flux of immigrants from different nations.

Some of the main differences in the Spanish spoken around the world are accent, forms of address, and the pronunciation of certain letters. When it comes to accents, the Spanish spoken outside of Spain can be divided in several general groups: Caribbean, Central America, North America or Mexico, South American, and RioPlatense, a specific variation of Spanish spoken only in Argentina, Uruguay, and Paraguay.

Spanish has two singular pronouns for the second person: tú (informal) and usted (formal). These are used uniformly around the world, except in RioPlatense Spanish, where a third form is the norm. Known as voseo, Spanish speakers of certain areas use vos as the informal variant. In Ecuador, vos is becoming popular, although it's not used in the media or outside the company of close friends. The use of different forms influences the accompanying verb. For example, to say "Come here" you would say "Venga aca," (usted), "Ven aca" (tú), "Veni aca" (vos).

When it comes to pronunciation, the main variants of Spanish are the sounds of letters s, c, and z and the y and the ll. In most Latin American countries, the sound of s and z have become standardized, which means it's hard to make out the difference between words like casa (house) and caza (hunt). In Spain, however, the distinction is strong, and confusing both letters is considered a sign of the uneducated class. The ll is pronounced soft, in a sound similar to the word "lieu" or, sometimes, the sound "iu," in most countries except RioPlatense Spanish, where a phenomenon called yeismo occurs. There, the letter ll sounds like /ʝ/ and sometimes /ʒ/.