Spanish belongs to the Romance branch of the Indo-European language family. Like all Romance languages, Spanish developed from Vulgar Latin in an area of the Iberian peninsula that is now Spain, and was brought to the Americas, the Philippines, and parts of Oceania by the Spanish colonization in the 16th century. It is spoken as a first language in 30 countries world-wide by about over 399 million and as a second language by some 89.5 million people (Ethnologue). Mexico has the largest population of Spanish first-language speakers in the world (103 million). The four next largest Spanish-speaking populations reside in Colombia (41 million), Spain (38.6 million), Argentina (38.8 million) and U.S. (34.2 million based on 2010 census). It is the fourth most spoken language in the world after Chinese, Hindi, and English.

Spaniards call their language español when contrasting it with other national languages. They refer to it as castellano (Castilian) when contrasting it with other regional languages of Spain, e.g., Catalan, Galician, or Basque. Other Spanish-speaking countries tend to use one or the other of the two terms.

Spanish is the official (or national) language of Argentina, Bolivia (with Quechua and Aymara), Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, Equatorial Guinea (with French), Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay (with Guarani), Peru (with Quechua and Aymara), Puerto Rico (with English), Spain (co-official in some regions with Catalan, Galician and Basque), Uruguay, Venezuela. In the United States, Spanish is the most studied foreign language in schools and universities. Spanish has co-official status in the state of New Mexico, and in Puerto Rico. It is is one of the six official working languages of the United Nations and one of twenty-three official languages of the European Union.

Dialects

Since Spanish is spoken by so many people in so many countries it is not surprising that it has developed a number of different dialects. The classic division is usually made between Spanish from Spain, or Castilian Spanish, and Spanish from Latin America. Within each division there are variations involving pronunciation, grammar, vocabulary, and intonation. Despite many regional differences, speakers of Spanish from different countries can understand each other without much difficulty. Examples of differences are given below.

• Pronunciation
  Castilian voiceless interdental fricative [θ], as in thin, does not exist in Latin American Spanish where ciento ‘hundred’ and siento ‘I am sorry’ are both pronounced with an initial [s]. In most of Spain, however, ciento is pronounced with an initial [θ].
• Grammar
  The 2nd person plural pronoun vosotros is the plural form of tu in most of Spain, but in the Americas it is replaced by ustedes. There are corresponding differences in the verb endings.
• Vocabulary
  Anybody who has studied Spanish knows how frustrating it can be to discover that a word in a Spanish textbook may not be used in some Spanish-speaking countries at all, or have a different meaning. For instance, the word for ‘computer’ is el ordenador in Spain, but computadora in Latin America. The word for ‘bus’ is guagua in Puerto Rico, but in Chile it means ‘baby’.

The sound system of Spanish is relatively uncomplicated.

Vowels
Spanish has five vowel phonemes, i.e., sounds that make a difference in word meaning. In addition, Spanish has several diphthongs, such as /ui/ as in muy ‘very.’

Consonants
Spanish has 19-20 consonant phonemes, i.e., sounds that differentiate word meaning. The chart below is based on Iberian Spanish. There are dialectal differences.

• /p, t, k/ are not aspirated, i.e., they are produced without a puff of air, as in English.
• /b/ has two realizations: as voiced bilabial stop [b] at the beginning of words and after nasal consonants, e.g., barrio, bamba; between vowels it is realized as a voiced bilabial approximant [β], e.g., cabo ‘cape’ is pronounced as [kaβo].
• /d/ has two realizations: as a voiced dental stop [d] at the beginning of words and after nasal consonants, e.g., dar ‘to give’, donde ‘where’, and as avoiced interdental fricative [ð], like th in those, between vowels, e.g., hablado ‘spoken’ is pronounced as [ablaðo].
• /θ/ = th in thin; it does not occur in Latin American Spanish that uses /s/ instead.
• /x/ has no equivalent in English.
• /ʝ/ has no equivalent in English; it occurs in words such as yo ‘I’. In some dialects it sounds more like s in vision.
• /tʃ/ = ch in chat
• /ɲ/ = first n in canyon
• /ʎ/ = ll in million
• There are two different /r/ phonemes: one is an alveolar tap, e.g., pero ‘but’, the other is an alveolar trill, e.g., perro ‘dog’. Only the trill can occur at the beginning of words.

Stress
Spanish is a syllable-timed language. In a syllable-timed language, every syllable takes up roughly the same amount of time, in contrast to a stress-timed language, such as English, in which stressed syllables take up more time than unstressed ones. Stress can occur on any syllable. 
 

Like other Romance languages, Spanish developed from Latin. As a result, its grammar shares many features with other Romance languages.

Nouns, adjectives, articles, and pronouns

• Spanish nouns are marked for gender (masculine, feminine) and number (singular, plural).
• There are no cases.
• Articles and adjectives agree in gender and number with the nouns they modify. Adjectives follow nouns, e.g., el/un hombre simpático ‘the/a nice man’, la/una mujer simpática ‘the/a nice woman’, los/unos hombres simpáticos ‘the/some nice men’, las/unas mujeres simpáticas ‘the/some nice women’.
• Latin American Spanish has only one form of the 2nd person plural — ustedes— which is used for both informal and formal address. In contrast, Iberian Spanish has two forms: ustedes (formal) and vosotros (informal). In Argentina and Uruguay, Vos ‘you‘ (singular, formal) is used as the primary form of 2nd person singular.

Verbs

• There are three regular conjugations that can be identified by the infinitive ending, for example, cantar ‘to sing’, comer ‘to eat’, vivir ‘to live’.There are many irregular verbs.
• Verbs agree with their subjects in person (1st, 2nd, 3rd) and number (singular, plural).
• There are three tenses (present, past, future). Compound tenses are formed with the auxiliary verb haber ‘to have’.
• There are four moods: indicative, conditional, subjunctive, imperative.
• Pronoun subjects are normally dropped since the verb endings carry information about person and number, e.g., canto ‘I sing’.
• There are two voices: active and passive.

Word order
The normal word order in Spanish declarative sentences is Subject-Verb-Object, e.g., Juan está leyendo un libro ‘John is reading a book.’ In questions, the normal word order is Question Word-Verb-Subject, e.g., ¿Qué está haciendo Juan?, ‘What is Juan doing?’

Spanish vocabulary is Latin-based with a large number of borrowings from Arabic, and more recently from English. Spain’s Arabic connection goes back to the invasion of Spain by Arabic-speaking Moors in 711 AD. Spanish and Arabic coexisted side by side until the Moors were expelled in the 15th century AD. By then thousands of Arabic words had become part of Spanish. Many of them start with al-, the definite article in Arabic. Many Spanish place names can be traced to Arabic, e.g., Alhambra from Arabic al-hamrâ ‘the red (castle)’. You will recognize some of these words as they are very similar to English words. Below are a few examples of such words:

Latin American Spanish has also borrowed words from the Indian languages of Central and South America. English, in turn, borrowed these words from Spanish.

Below are some common words and phrases in Spanish.

It must be noted that there are some differences in vocabulary among the Spanish-speaking countries. For instance, the word for bus in Spain is autobús, but in Puerto Rico it is guagua. However, the word guagua in Chile means ‘baby’.  In some Latin American countries the word for avocado is aguacate, while in others it ispalta.

Below are the numerals 1-10 in Spanish.

Writing

Written Spanish first appeared in notes and glosses in Latin religious texts in the 11th century. In the 12th century, law codes were translated into Spanish. The 13th century gave rise to Spanish prose. The first Spanish grammar and dictionaries were published in the 15th-16th centuries.

Spanish is written with the Latin alphabet that includes one extra letter Ñ ñ. It is given below.

• The acute accent is used over the vowels á, é, í, ó, ú is an integral part of Spanish orthography; it is used to mark stress when it does not follow the normal pattern, or to differentiate words that otherwise sound alike.
• ñ = first n in canyon
• Spanish precedes interrogative and exclamatory clauses with inverted question and exclamation marks, e.g., ¿Que pasa? ‘What’s up?’ or ¡No me digas! ‘Don’t tell me!’
• h is always silent.
• c and z are pronounced as [θ] (th in thin) in most of Spain and as [s] in Latin America.
• d is pronounced as [ð] (th in those) between vowels, and as [d] elsewhere, e.g., dar ‘to give’ is pronounced as [dar], and hablado ‘spoken’ is pronounced as [ablaðo].
• g is pronounced as a voiceless velar fricative [x] (ch as in German pronunciation of Bach) or voiceless glottal fricative [h] (h as in hat) before i and e, and as [g] elsewhere, e.g., gato ‘cat’ is pronounced as [gato], gente ‘people’ is pronounced as [xente] or [hente].
• There is no difference in the pronounciation of b and v. Both are pronounced as [b] at the beginning of words and after nasal consonants, e.g., barrio,bamba. Elsewhere, both are pronounced as a voiced bilabial approximant [β], e.g., cabo ‘cape’ is pronounced as [kaβo].
• ll is pronounced as a voiced palatal approximant [ʝ], e.g., calle ‘street is pronounced as [kaʝe].
• k occurs only in borrowings and foreign names.
•  

Take a look at Article 1 of the Universal Declaration of Human Rights in Spanish.

English has borrowed many words from Spanish. Below are just a few of them.