In Ancient Greek, Υψιλον (Upsilon) represented /u/, then later on /y/ — close front rounded vowel. The Romans had already borrowed this as the letter V, to represent both the vowel /u/ as well as the consonant /w/, but in later times, because the pronunciation of Ypsilon in Greek had shifted to /y/, they borrowed it directly in its original form, stem and all, as Y — mainly to represent names and words taken from Greek.
The letter Y was used in Old English, as in Latin, to represent /y/; however, some claim that this use was an independent invention in England created by stacking a V and an I, unrelated to the Latin use of the letter. Regardless, it is fairly likely that the letter, although technically named Y Græca (IPA ) meaning 'Greek u' in contradistinction from native Latin /u/, came to be analyzed as the letter V (called /uː/) atop the letter I (called /iː/). The letter was thus referred to as , which after /uː/ became the glide /w/ and after English's Great Vowel Shift naturally became /waɪ/.
By Middle English, /y/ had lost its roundedness and merged with /i/, and Y came to be used with the same values as I, /iː/ and /ɪ/ as well as /j/. Those dialects that retained /y/ spelled it with U, under French influence.
The Modern English use of Y is a direct continuation of this Middle English use. Thus the words myth [of Greek origin] and gift [of Old English origin], which originally contained high front rounded vowels, both have [ɪ].
With the introduction of printing, the letter Y was used by Caxton and other printers in England to represent the letter thorn (Þ, þ) which was lacking from continental typefaces, resulting in the use of ye for the word the.
After fronting from /u/, Greek /y/ de-rounded to /i/.
In Dutch, Y appears only in loanwords and names and usually represents /i/. It is often left out of the Dutch alphabet and replaced with the "ligature IJ". In Afrikaans, a development of Dutch, Y denotes the diphthong [EI], probably as a result of mixing lower case i and y or may derive from the IJ ligature.
In the Spanish language, Y was used as a word-initial form of I that was more visible. (German has used J in a similar way.) Hence el Yugo y las Flechas was a symbol sharing the initials of Isabella I of Castille (Ysabel) and Ferdinand II of Aragon. This spelling was reformed by the Royal Spanish Academy and currently is only found in proper names spelt archaically, such as Ybarra or CYII, the symbol of the Canal de Isabel II. X is also still used in Spanish with a different sound in some archaisms.
Appearing alone as a word, the letter Y is a grammatical conjunction with the meaning "and" in Spanish and is pronounced /i/. In Spanish family names, y can separate the father's surname from the mother's surname as in "Santiago Ramón y Cajal". Catalan names use i for this. Otherwise, Y represents /[[ʝ]]/ in Spanish. When coming before the sound /i/, Y is replaced with E: "español e inglés". This is to avoid pronouncing /i/ twice.
The letter Y is called "I/Y griega", the "Greek I", after the Greek letter Ypsilon.
In Lithuanian Y is the 15th letter and is a vowel. It is called the long i and is pronounced /i:/ like in English see.
In Azerbaijani Y is pronounced as ya.
When used as a vowel in Vietnamese, the letter y represents the close front unrounded vowel. When used as a monophthong, it is functionally equivalent to the Vietnamese letter i. Thus, Mỹ Lai does not rhyme but mỳ Lee does. There have been efforts to replace all such uses with i altogether, but they have been largely unsuccessful.
It is indicative of the rarity of front rounded vowels that [y] is the rarest sound represented in the IPA by a letter of the Latin alphabet, being cross-linguistically less than half as frequent as [q] or [c] and only about a quarter as frequent as [x].
The EBCDIC code for capital Y is 232 and for lowercase y is 168.
af:Y als:Y ar:Y arc:Y ast:Y az:Y ca:Y cs:Y co:Y cy:Y da:Y de:Y et:Y el:Y es:Y eo:Y eu:Y fa:Y fur:Y gan:Y gd:Y gl:Y ko:Y hr:Y ilo:Y is:Y it:Y he:Y ka:Y kw:Y sw:Y ht:Y la:Y lv:Y lt:Y hu:Y ms:Y mzn:Y nah:Y ja:Y no:Y nn:Y nrm:Y pl:Y pt:Y ro:Y qu:Y simple:Y sk:Y sl:Y fi:Y sv:Y tl:Y th:Y vi:Y vo:Y yo:Y zh-yue:Y bat-smg:Y zh:Y