The Vietnamese alphabet contains 29 letters, including one digraph (đ) and nine with diacritics, five of which are used to designate tone (a, à, á, ả, ã, and ạ) and the other four used for separate letters of the Vietnamese alphabet (ă, â/ê/ô, ơ, ư ). The large number of diacritics, often two on the same letter, makes it one of the most recognizable amongst Latin alphabets