In Afrikaans, Catalan, Dutch, French, Galician, Welsh, Southern Sami, and occasionally English, ⟨ï⟩ is used when ⟨i⟩ follows another vowel and indicates hiatus (diaeresis) in the pronunciation of such a word. It indicates that the two vowels are pronounced in separate syllables, rather than together as a diphthong or digraph. For example, French maïs (IPA: [ma.is], maize); without the diaeresis, the ⟨i⟩ is part of the digraph ⟨ai⟩: mais (IPA: [mɛ], but). The letter is also in Dutch Oekraïne (pronounced [ukraːˈinə], Ukraine), and English naïve (// or //).
In scholarly writing on Turkic languages, ⟨ï⟩ is sometimes used to write the close back unrounded vowel /ɯ/, which, in the standard modern Turkish alphabet, is written as the dotless i ⟨ı⟩. The back neutral vowel reconstructed in Proto-Mongolic is sometimes written ⟨ï⟩.
Lowercase ï occurs in the sequence ï»¿, which is the Unicode byte order mark in UTF-8 misinterpreted as ISO-8859-1 or CP1252 (both common encodings in software configured for English-language users). Thus, it tends to indicate that any following mojibake can be corrected by reinterpreting it as UTF-8.
|Unicode name||LATIN CAPITAL LETTER I WITH DIAERESIS||LATIN SMALL LETTER I WITH DIAERESIS|
|UTF-8||195 143||C3 8F||195 175||C3 AF|
|Numeric character reference||Ï||Ï||ï||ï|
|Named character reference||Ï||ï|