<P> The letter J originated as a 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 representing 23 . A distinctive usage emerged in Middle High German . 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 . Originally , ' I ' and ' J ' were different shapes for the same letter , both equally representing / i / , / iː / , and / j / ; but , 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 word `` yet '' ) . </P>
when was the letter j introduced to the alphabet
1524