Í, í (i-acute) is a letter in the Faroese, Hungarian, Icelandic, Karakalpak, Dobrujan Tatar, Czech, and Slovak languages, where it often indicates a long /i/ vowel (ee in English word feel). This form also appears in Catalan, Irish, Italian, Occitan, Portuguese, Spanish, Aragonese, Galician, Leonese, Navajo, and Vietnamese language as a variant of the letter "i". In Latin, the long i ⟨ꟾ⟩ is used instead of ⟨í⟩ for a long i-vowel.

In Chinese pinyin í is the yángpíng tone (阳平, high-rising tone) of “i”.

Í is the 12th letter of the Dobrujan Tatar alphabet, represents the hight unrounded half-advanced ATR or soft vowel /ɨ/ as in "bír" [b̶ɨr̶] 'one'. At the end of the word it is pronounced with half open mouth undergoing dilatation "Keñiytúw" and becoming mid unrounded half-advanced ATR or soft /ə/, also known as schwa, as in "tílí" [t̶ɨl̶ə] 'his tongue'.

Í is the 11th letter of the Faroese alphabet and represents /ʊi/.

Í is the 16th letter of the Hungarian alphabet, the 12th letter of the Icelandic alphabet, the 16th letter of the Czech alphabet and the 18th letter of the Slovak alphabet. It represents /iː/.

In Ibero-Romance languages, the "í" is not considered a letter, but the letter "i" with an accent. It is used to denote an "i" syllable with abnormal stress. In Italian, Í/í is a variant of I carrying an acute accent; it represents an /i/ carrying the tonic accent. It is used only if it is the last letter of the word except in dictionaries or when a different pronunciation may affect the meaning of a word: víola ("violates", pronounced [ˈviːola]) and viòla ("violet", pronounced ['vjɔːla]).

Í is the 13th letter of the Karakalpak alphabet. It represents /ɯ/. Its preferred lowercase form is ⟨ı⟩.

In Vietnamese alphabet í is the sắc tone (high-rising tone) of “i”.