The Portuguese alphabet uses 23 letters of the Latin alphabet, as follows:
They are used both in uppercase or lowercase forms.
Due to the Portuguese language's use in many countries worldwide, there are several different standard spoken and written versions. This makes Portuguese a pluricentric language.
Portuguese is a stressed language. For example, if a word ends with the vowels "a", "e", "o" and "u", the stress is placed on the penultimate syllable. For words that end with an "i", the stress falls on the preceding vowel.
Stress in placed on the last syllable for words which end with one of the consonants "m", "r", "l" and "z". Stress falls on the next-to-last syllable for words which end with an "s". An exception to this rule occurs if the word ends with "am" or "em". In these cases, the stress is placed on the second-to-last vowel.
Diphthongs, a speech sound or glide which begins with one vowel and gradually changes to another vowel within the same syllable, have a stress rule as well. If a vowel diphthong is located where the stress would normally fall, stress is placed on the first syllable. Diphthongs found in Portuguese are "ai", "ei", "oi", "ou", "eu", "iu" and "ao".
Written Portuguese is similar to Spanish, however, the spelling of some words are determined by Latin which may make it difficult to determine pronunciation as sound values can be written in multiple ways.
Although the letter "h" is silent, except for interjections such as "ha!" or "oh!" it is included in the spelling of Portuguese words. When "m" and "n" follow a vowel, that vowel is nasalized. "R" can be pronounced as strong "r" or a weak "r". The strong "r" sound is articulated if the "r" is at the beginning of a word, following a consonant or if it is doubled. "S" is pronounced as a "z" when it is located between two vowels. Otherwise, it is pronounced "s". The character "x" has five different pronunciations, depending on where it is located in the word and whether the adjacent letters are vowels or consonants.
Portuguese utilizes digraphs and trigraphs to form supplementary sounds. Common digraphs and trigraphs are "ch", "lh", "nh", "rr", "sc", "ss", "qu" "xc", "zz" and "tch". The digraphs "zz" and "tch" are rarely used. Syllable breaks are mandatory to divide the digraphs "rr", "ss" and "xc" (i.e. "r-r").
Portuguese has fourteen vowels sounds and diacritics are utilized to assist in pronunciation. Diacritics currently in use are:
Á, Â, Ã, À, Ç, É, Ê, Í, Ó, Ô, Õ, and Ú
Diacritics are not treated as individual letters. They do not have their own entries in Portuguese dictionaries and are alphabetized according to whether the word has a diacritic. Letters without diacritics are listed first.
Compound words are created with the use of the hyphen (-). Hyphens append weak pronouns to verbs or embeds them in the verb.
The letters "k", "w" and "y" were used until the 1940's. They were removed from the alphabet in accordance with a spelling reform agreement between Portugal and Brazil. "C", "u" or "v", and "i" replaced those sound values. Now they are only found in loan words and proper names. When the latest spelling reform of 1990 comes into effect in 2009, these letters will once again form part of the Portuguese alphabet.
The institutions of Academias de Letras situate in Portugal and Brazil are mandated to further cultivation of the Portuguese language.