The official Latin-based Vietnamese alphabet consists of 29 letters: 17 consonants and 12 vowels. Except f, j, w, and z, 22 letters come from the Roman alphabet. Seven letters are modified with diacritics: ă, â, đ, ê, ô, ơ, and ư. As in English, the order follows the Roman alphabetic convention. Letters without diacritical marks come before letters with diacritical marks. For instance, a precedes ă and d precedes đ. The following alphabetization is taught in schools.
Vietnamese has an extensive number of letters with diacritical marks to make tonal distinctions. The ordering of tone marks is varied, but one of the most common systems is Nguyễn Đình Hòa’s: unmarked tone (ngang), acute (sắc), grave (huyền), hook above (hỏi), tilde (ngã), and underdot (nặng).1 Because diacritics play an essential role in differentiating the vowel qualities, each vowel can be combined with one or two marks. The following 134 letters (uppercase and lowercase) demonstrate all the possibilities of diacritics in Vietnamese.