The Vietnamese alphabet (Vietnamese: chữ Quốc ngữ, lit. 'script of the National language') is the modern Latin writing script or writing system for romanized Vietnamese. It uses the Latin script based on Romance languages^[6] originally developed by Portuguese missionary Francisco de Pina (1585–1625).^[1]

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The Vietnamese alphabet contains 29 letters, including seven letters using four diacritics: ⟨ă⟩, ⟨â⟩, ⟨ê⟩, ⟨ô⟩, ⟨ơ⟩, ⟨ư⟩, and ⟨đ⟩. There are an additional five diacritics used to designate tone (as in ⟨à⟩, ⟨á⟩, ⟨ả⟩, ⟨ã⟩, and ⟨ạ⟩). The complex vowel system and the large number of letters with diacritics, which can stack twice on the same letter (e.g. nhất meaning 'first'), makes it easy to distinguish the Vietnamese orthography from other writing systems that use the Latin script.^[7]

The Vietnamese system's use of diacritics produces an accurate transcription for tones despite the limitations of the Roman alphabet. On the other hand, sound changes in the spoken language have led to different letters, digraphs and trigraphs now representing the same sounds.

Vietnamese uses 22 letters of the ISO basic Latin alphabet. The four remaining letters are not considered part of the Vietnamese alphabet although they are used to write loanwords, languages of other ethnic groups in the country based on Vietnamese phonetics to differentiate the meanings or even Vietnamese dialects, for example: ⟨dz⟩ or ⟨z⟩ for southerner pronunciation of ⟨v⟩ in standard Vietnamese.

In total, there are 12 vowels (nguyên âm) and 17 consonants (phụ âm, literally 'extra sound').

Notes

• The vowels in the table are bolded and italicized.
• The use of the terms bê or bờ to refer to ⟨b⟩ and as pê or pờ to refer to ⟨p⟩ is to avoid confusion in some contexts, the same for ⟨s⟩ as sờ mạnh or sờ nặng. (literally, 'strong s' or 'heavy s') and ⟨x⟩ as xờ nhẹ (literally, 'light x'), ⟨i⟩ as i ngắn (literally, 'short i') and ⟨y⟩ as y dài (literally, 'long y').
• ⟨q⟩ is always followed by ⟨u⟩ in every word and phrase in Vietnamese, e.g. quần 'trousers', quyến rũ 'to attract', etc.
• The name i-cờ-rét for ⟨y⟩ is from the French name for the letter: i grec (literally, 'Greek i'),^[9] referring to the letter's origin from the Greek letter upsilon. The other obsolete French pronunciations include ⟨e⟩ (/əː˧/) and ⟨u⟩ (/wi˧/).
• The Vietnamese alphabet does not contain the 4 letters ⟨f⟩ (ép, ép-phờ), ⟨j⟩ (gi), ⟨w⟩ (u kép 'double u', vê kép, vê đúp 'double v') and ⟨z⟩ (giét). However, these letters are often used for foreign loanwords (even partially adapted ones: flo 'fluorine', jun 'joule', bazơ 'base') or may be kept for foreign names.
• ⟨y⟩ is most commonly treated as a vowel along with ⟨i⟩. ⟨i⟩ represents 'short /i˧/' and ⟨y⟩ represents 'long /i˧/'. ⟨y⟩ can have tones as well as other vowels (⟨ý⟩, ⟨ỳ⟩, ⟨ỹ⟩, ⟨ỷ⟩, ⟨ỵ⟩) e.g. Mỹ 'America'. It may also act as a consonant (when used after ⟨â⟩ and ⟨a⟩). It can sometimes be used to replace ⟨i⟩, e.g. bánh mì 'bread' can also be written bánh mỳ.
• ⟨s⟩ and ⟨x⟩ are similar to each other in sound in Vietnamese and can sometimes replace each other e.g. sương xáo or sương sáo 'grass jelly'.

The alphabet is largely derived from Portuguese with some influence from French^{[citation needed]}, although the usage of ⟨gh⟩ and ⟨gi⟩ was borrowed from Italian (compare ghetto, Giuseppe) and that for ⟨c, k, qu⟩ from (Latinised) Greek and Latin (compare canis, kinesis, quō vādis), mirroring the English usage of these letters (compare cat, kite, queen).

10 digraphs consist: ⟨ch⟩, ⟨gh⟩, ⟨gi⟩, ⟨kh⟩, ⟨ng⟩, ⟨nh⟩, ⟨ph⟩, ⟨qu⟩, ⟨th⟩, ⟨tr⟩, and only one trigraph ⟨ngh⟩.

Vietnamese is a tonal language, so the meaning of each word depends on the pitch in which it is pronounced. Tones are marked in the IPA as suprasegmentals following the phonemic value. Some tones are also associated with a glottalization pattern.

There are six distinct tones in the standard northern dialect. The first one ("level tone") is not marked and the other five are indicated by diacritics applied to the vowel part of the syllable. The tone names are chosen such that the name of each tone is spoken in the tone it identifies.

In the south, there is a merging of the hỏi and ngã tones, in effect leaving five tones.^{[citation needed]}

• * = Z (in TELEX) and 0 (in VNI) keys are used to remove the mark. For example, in TELEX, AS => ⟨á⟩, then press Z => ⟨a⟩.
• Unmarked vowels are pronounced with a level voice, in the middle of the speaking range.
• The grave accent indicates that the speaker should start somewhat low and drop slightly in tone, with the voice becoming increasingly breathy.
• The hook indicates in Northern Vietnamese that the speaker should start in the middle range and fall, but in Southern Vietnamese that the speaker should start somewhat low and fall, then rise (as when asking a question in English).
• In the North, a tilde indicates that the speaker should start mid, break off (with a glottal stop), then start again and rise like a question in tone. In the South, it is realized identically to the Hỏi tone.
• The acute accent indicates that the speaker should start mid and rise sharply in tone.
• The dot or cross signifies in Northern Vietnamese that the speaker starts low and fall lower in tone, with the voice becoming increasingly creaky and ending in a glottal stop.

In syllables where the vowel part consists of more than one vowel (such as diphthongs and triphthongs), the placement of the tone is still a matter of debate. Generally, there are two methodologies, an "old style" and a "new style". While the "old style" emphasizes aesthetics by placing the tone mark as close as possible to the center of the word (by placing the tone mark on the last vowel if an ending consonant part exists and on the next-to-last vowel if the ending consonant does not exist, as in hóa, hủy), the "new style" emphasizes linguistic principles and tries to apply the tone mark on the main vowel (as in hoá, huỷ). In both styles, when one vowel already has a quality diacritic on it, the tone mark must be applied to it as well, regardless of where it appears in the syllable (thus thuế is acceptable while *thúê is not). In the case of the ⟨ươ⟩ diphthong, the mark is placed on the ⟨ơ⟩. The ⟨u⟩ in ⟨qu⟩ is considered part of the consonant. Currently, the new style is usually used in textbooks published by Nhà Xuất bản Giáo dục, while most people still prefer the old style in casual uses. Among Overseas Vietnamese communities, the old style is predominant for all purposes.

In lexical ordering, differences in letters are treated as primary, differences in tone markings as secondary and differences in case as tertiary differences. (Letters include for instance ⟨a⟩ and ⟨ă⟩ but not ⟨ẳ⟩. Older dictionaries also treated digraphs and trigraphs like ⟨ch⟩ and ⟨ngh⟩ as base letters.^[10]) Ordering according to primary and secondary differences proceeds syllable by syllable. According to this principle, a dictionary lists tuân thủ before tuần chay because the secondary difference in the first syllable takes precedence over the primary difference in the second syllable.

In the past, syllables in multisyllabic words were concatenated with hyphens, but this practice has died out and hyphenation is now reserved for word-borrowings from other languages. A written syllable consists of at most three parts, in the following order from left to right:

1. An optional beginning consonant part
2. A required vowel syllable nucleus and the tone mark, if needed, applied above or below it
3. An ending consonant part, can only be one of the following: ⟨c⟩, ⟨ch⟩, ⟨m⟩, ⟨n⟩, ⟨ng⟩, ⟨nh⟩, ⟨p⟩, ⟨t⟩, or nothing.^[11]

Since the beginning of the Chinese rule 111 BC, literature, government papers, scholarly works, and religious scripture were all written in classical Chinese (chữ Hán) while indigenous writing in chữ Hán started around the ninth century.^[12] Since the 12th century, several Vietnamese words started to be written in chữ Nôm, using variant Chinese characters, each of them representing one word. The system was based on chữ Hán, but was also supplemented with Vietnamese-invented characters (chữ thuần nôm, proper Nôm characters) to represent native Vietnamese words.

• Portuguese orthography
• Special characters:
  • Ă, Â, Đ, Ê, Ô, Ơ, Ư
  • Dot (diacritic)
  • Hook above
  • Horn (diacritic)
• Historic Writing
  • "Chữ Hán", classical Chinese written in Vietnam (Han characters)
  • "Chữ Nôm", former script used to write Vietnamese using Han and Nom (invented characters) words
• Coding and Input Methods:
  • Telex, the oldest standard input method for the Vietnamese alphabet on electronic devices.
  • VNI, another input and encoding convention for Vietnamese alphabet.
  • VIQR, another standard 7-bit input method for Vietnamese alphabet.
  • VISCII, another standard 8-bit encoding for Vietnamese alphabet.
  • Unicode, character encoding standard for most of the world's writing systems
• Vietnamese Braille
• Vietnamese calligraphy
• Vietnamese phonology
• Francisco de Pina
• Alexandre de Rhodes