The official Latin-based Vietnamese alphabet consists of twenty-nine letters: seventeen consonants and twelve vowels. Twenty-two letters come from the Roman alphabet (minus f, j, w, and z). Seven letters have been modified: ă, â, đ, ê, ô, ơ, and ư. As in English, the order follows the Roman alphabetic convention. Letters with diacritical marks come after letters without. 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 the most common is Nguyễn Đình Hòa’s convention: 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 tones, each vowel can take on one or two additional marks. The following 134 letters (uppercase and lowercase) demonstrate all the possibilities of diacritics in Vietnamese.