J

In English, ⟨j⟩ most commonly represents the affricate /dʒ/. In Old English, /dʒ/ was represented orthographically with ⟨cᵹ⟩[8] (equivalent to ⟨cg⟩, as ⟨ᵹ⟩ in Old English was simply the regular form of the letter G, called Insular G). Middle English scribes began to use ⟨i⟩ (later ⟨j⟩) to represent word-initial /dʒ/ under the influence of Old French, which had a similarly pronounced phoneme deriving from Latin /j/ (for example, iest and later jest), while the same sound in other positions could be spelled as ⟨dg⟩ (for example, hedge).[8] The first English language books to make a clear distinction in writing between ⟨i⟩ and ⟨j⟩ were the King James Bible 1st Revision Cambridge 1629 and an English grammar book published in 1633.[9]

Later, many other uses of ⟨i⟩ (later ⟨j⟩) were added in loanwords from French and other languages (e.g. adjoin, junta). In loanwords such as bijou or Dijon, ⟨j⟩ may represent /ʒ/, as in modern French. In some loanwords, including raj, Azerbaijan, Taj Mahal, and Beijing, the regular pronunciation /dʒ/ is actually closer to the native pronunciation, making the use of /ʒ/ an instance of hyperforeignism, a type of hypercorrection.[10] Occasionally, ⟨j⟩ represents its original /j/ sound, as in Hallelujah and fjord (see Yodh for details). In words of Spanish origin, such as jalapeño, English speakers usually pronounce ⟨j⟩ as the voiceless glottal fricative /h/, an approximation of the Spanish pronunciation of ⟨j⟩ (usually transcribed as a voiceless velar fricative [x], although some varieties of Spanish use glottal [h]).

In English, ⟨j⟩ is the fourth least frequently used letter in words, being more frequent only than ⟨z⟩, ⟨q⟩, and ⟨x⟩. It is, however, quite common in proper nouns, especially personal names.

The great majority of Germanic languages, such as German, Dutch, Icelandic, Swedish, Danish and Norwegian, use ⟨j⟩ for the palatal approximant /j/, which is usually represented by the letter ⟨y⟩ in English. Notable exceptions are English, Scots and (to a lesser degree) Luxembourgish. ⟨j⟩ also represents /j/ in Albanian, and those Slavic and Baltic languages that use the Latin alphabet, such as Polish, Czech, Serbo-Croatian, Slovak, Slovenian, Latvian and Lithuanian. Some related languages, such as Serbo-Croatian and Macedonian, also adopted ⟨j⟩ into the Cyrillic alphabet for the same purpose. Because of this standard, the lower case letter was chosen to be used in the IPA as the phonetic symbol for the sound.

In the Romance languages, ⟨j⟩ has generally developed from its original palatal approximant value in Latin to some kind of fricative. In French, Portuguese, Catalan (except Valencian), and Romanian it has been fronted to the postalveolar fricative /ʒ/ (like ⟨s⟩ in English measure). In Valencian and Occitan it has the same sound as in English, /dʒ/. In Spanish, by contrast, it has been both devoiced and backed from an earlier /ʝ/ to a present-day /x/ or /h/,[11] with the actual phonetic realization depending on the speaker's dialect.

Generally, ⟨j⟩ is not commonly present in modern standard Italian spelling. Only proper nouns (such as Jesi and Letojanni), Latin words (Juventus), or those borrowed from foreign languages have ⟨j⟩. The proper nouns and Latin words are pronounced as the palatal approximant /j/, while words borrowed from foreign languages tend to follow that language's pronunciation of ⟨j⟩. Until the 19th century, ⟨j⟩ was used instead of ⟨i⟩ in diphthongs, as a replacement for final -ii, and in vowel groups (as in Savoja); this rule was quite strict in official writing. ⟨j⟩ is also used to render /j/ in dialectal spelling, e.g. Romanesco dialect ⟨ajo⟩ [ajo] (garlic; cf. Italian aglio [aʎo]). The Italian novelist Luigi Pirandello used ⟨j⟩ in vowel groups in his works written in Italian; he also wrote in his native Sicilian language, which still uses the letter ⟨j⟩ to represent /j/ (and sometimes also [dʒ] or [gj], depending on its environment).[12]

The Maltese language is a Semitic language, not a Romance language; but has been deeply influenced by them (especially Sicilian) and it uses ⟨j⟩ for the sound /j/ (cognate of the Semitic yod).

In Basque, the diaphoneme represented by ⟨j⟩ has a variety of realizations according to the regional dialect: [j, ʝ, ɟ, ʒ, ʃ, x] (the last one is typical of Gipuzkoa).

The Uralic languages spoken in Europe use ⟨j⟩ for [j].

Among non-European languages that have adopted the Latin script, ⟨j⟩ stands for /ʒ/ in Turkish and Azerbaijani, for /ʐ/ in Tatar. ⟨j⟩ stands for /dʒ/ in Indonesian, Somali, Malay, Igbo, Shona, Oromo, Turkmen, and Zulu. It represents a voiced palatal plosive /ɟ/ in Konkani, Yoruba, and Swahili. In Kiowa, ⟨j⟩ stands for a voiceless alveolar plosive, /t/.

⟨j⟩ stands for /dʒ/ in the romanization systems of most of the languages of India such as Hindi and Telugu and stands for /dʑ/ in the romanization of Japanese and Korean.

For Chinese languages, ⟨j⟩ stands for /t͡ɕ/ in Mandarin Chinese Pinyin system, the unaspirated equivalent of ⟨q⟩ (/t͡ɕʰ/). In Wade–Giles, ⟨j⟩ stands for Mandarin Chinese /ʐ/. Pe̍h-ōe-jī of Hokkien and Tâi-lô for Taiwanese Hokkien, ⟨j⟩ stands for /z/ and /ʑ/, or /d͡z/ and /d͡ʑ/, depending on accents. In Jyutping for Cantonese, ⟨j⟩ stands for /j/.

The Royal Thai General System of Transcription does not use the letter ⟨j⟩, although it is used in some proper names and non-standard transcriptions to represent either จ [tɕ] or ช [tɕʰ] (the latter following Pali/Sanskrit root equivalents).

In romanized Pashto, ⟨j⟩ represents ځ, pronounced [dz].

In Greenlandic and in the Qaniujaaqpait spelling of the Inuktitut language, ⟨j⟩ is used to transcribe /j/.

Following Spanish usage, ⟨j⟩ represents [x] or similar sounds in many Latin-alphabet-based writing systems for indigenous languages of the Americas, such as [χ] in Mayan languages (ALMG alphabet) and a glottal fricative [h] in some spelling systems used for Aymara.

In the Wingdings font by Microsoft, the letter "J" is rendered as a smiley face, sometimes creating confusion in emails after formatting is removed and a smiley turns back into an out-of-context "J".[22] (this is distinct from the Unicode code point U+263A, which renders as ☺︎). In Microsoft applications, ":)" is automatically replaced by a smiley rendered in a specific font face when composing rich text documents or HTML email. This autocorrection feature can be switched off or changed to a Unicode smiley.[23]