The diaeresis (/daɪˈɛrəsɪs, -ˈɪər-/ dy-ERR-ə-sis, -EER-; is a diacritical mark used to indicate the separation of two distinct vowels in adjacent syllables when an instance of diaeresis (or hiatus) occurs, so as to distinguish from a digraph or diphthong. It consists of two dots ¨ placed over a letter, generally a vowel; when that letter is an ⟨i⟩, the diacritic replaces the tittle: ⟨ï⟩.