In loanwords such as bijou or Dijon, ⟨j⟩ may represent /ʒ/, as in modern French. Later, many other uses of ⟨i⟩ (later ⟨j⟩) were added in loanwords from French and other languages (e.g. The first English language book to make a clear distinction in writing between ⟨i⟩ and ⟨j⟩ was the King James Bible 1st Revision Cambridge 1629 and an English grammar book published in 1633. Middle English scribes began to use ⟨i⟩ (later ⟨j⟩) to represent word-initial /dʒ/ under the influence of Old French, which had a similar phoneme deriving from Latin /j/ (for example, iest and later jest) the same sound in other positions could be spelled as ⟨dg⟩ (for example, he dge).

In Old English, /dʒ/ was represented orthographically with ⟨cg⟩ and ⟨cȝ⟩. In English, ⟨j⟩ most commonly represents the affricate /dʒ/. ʑ/ and / dʑ/ distinct in some dialects, see Yotsugana Most common pronunciation: / j/ Languages in italics do not use the Latin alphabet Pronunciation and use List of pronunciations Originally, 'I' and 'J' were different shapes for the same letter, both equally representing /i/, /iː/, and /j/ however, Romance languages developed new sounds (from former /j/ and /ɡ/) that came to be represented as 'I' and 'J' therefore, English J, acquired from the French J, has a sound value quite different from /j/ (which represents the initial sound in the English language word ' yet'). Gian Giorgio Trissino (1478–1550) was the first to explicitly distinguish I and J as representing separate sounds, in his Ɛpistola del Trissino de le lettere nuωvamente aggiunte ne la lingua italiana ('Trissino's epistle about the letters recently added in the Italian language') of 1524.

A distinctive usage emerged in Middle High German.

The letter J used to be used as the swash letter I, used for the letter I at the end of Roman numerals when following another I, as in XXIIJ or xxiij instead of XXIII or xxiii for the Roman numeral twenty-three. Children's book from 1743, showing I and J considered as the same letter

J&B Detectives by Julián Gómez-Munita