I

I is the ninth letter and third vowel of the Latin alphabet.¹¹ In the Unicode Standard it is the character U+0049 LATIN CAPITAL LETTER I, decimal code 73, with the lowercase i at U+0069.¹ In the Roman numeral system I represents 1, and in medieval Latin documents it could be written as i or j.² Until the early seventeenth century the standard Latin alphabet had 23 letters, with i and j considered letterforms of one letter, as were u and v.³

In the Unicode Standard it is the character U+0049 LATIN CAPITAL LETTER I, decimal code 73, with the lowercase i at U+0069.¹

Origin and history

The Latin alphabet grew out of a western Greek script that the Romans adopted; the dominant view holds that this happened indirectly, via the Etruscans, who reshaped it substantially to suit their own language. Up to the first century BC it comprised twenty-one letters (A to X), after which Y and Z were introduced, originally to write Greek names and foreign words.⁶

One letter, two shapes. Until the early seventeenth century the standard Latin alphabet contained 23 letters. The letters now known as i and j were considered different minuscule shapes of the same letter, as were u and v, and the letter w was not part of the standard alphabet at all. A printer's choice between the i and j letterforms depended on placement in the word and followed convention, which varied by printer and often reflected national and regional preferences. In the pre-modern distribution there was only one capital form, I (its gothic form resembling a modern J), used in all positions without signifying vocalic or consonantal use; lowercase i appeared in initial, medial, and final position, while j was used medially or finally only after a preceding i, a pattern more typical on the European continent.³ A gradual shift from the late fifteenth through the middle of the seventeenth century gave I/i the vowel value and J/j the consonant value, and in the modern 26-letter alphabet i and j are separate letters.³ The same history explains older spellings such as iustice for modern justice.³

I as a numeral

In the Roman numeral system I represents 1, and the letter served as a numeral sign in the products of the Roman mint.⁷ Medieval Latin documents carried the practice forward with their own conventions: Roman numerals were often written in lower case rather than capitals, and a number ending in i was often written with a final j. Thus 1 could appear as i or j, 2 as ii or ij, and 4 as iiii or iiij rather than the classical iv.² The same documents used Roman numerals throughout the period covered by standard dating tutorials, with Arabic numerals (1, 2, 3, and so on) appearing in England only from the sixteenth century onwards.²

Variants and derived characters

The letter i takes diacritics in many languages, and some of these marked forms are separately encoded. Turkish and Azerbaijani distinguish a dotted capital İ (U+0130, LATIN CAPITAL LETTER I WITH DOT ABOVE) from a dotless lowercase ı (U+0131, LATIN SMALL LETTER DOTLESS I), a pairing with no equivalent in English.⁴ Other encoded forms include Ĩ and ĩ (i with tilde), Ī and ī (i with macron, used in Latvian and Latin), Ĭ and ĭ (i with breve), and Į and į (i with ogonek, used in Lithuanian).⁴

Phonetic and specialized uses. The International Phonetic Alphabet, an extension of the Latin alphabet, uses U+026A ɪ LATIN LETTER SMALL CAPITAL I for the near-close front-unrounded vowel.⁵ Further specialized characters include U+1D7B ᵻ LATIN SMALL CAPITAL LETTER I WITH STROKE, used with different meanings by Americanists and Oxford dictionaries, and U+A7BD ꞽ LATIN SMALL LETTER GLOTTAL I, used for the Latin transliteration of yod in ancient Egyptian texts.^{8 • 9}

The Dutch digraph IJ, though often perceived as a single letter, is coded as two separate letters I and J in Dutch public-record practice; when a word beginning with IJ is capitalized, both letters are written as capitals.¹⁰

References

1. LATIN CAPITAL LETTER I (U+0049), Unicodepedia
2. Dating Latin documents, The National Archives (UK)
3. Appendix G4. Letterforms I/J, U/V, i/j, and u/v, Descriptive Cataloging of Rare Books, Cataloger's Reference Shelf
4. The Unicode Standard, Version 17.0, Latin Extended-A code chart (U+0100)
5. Unicode Names, SIL
6. Bernhard Bischoff, Latin Palaeography: Latin script in antiquity, Cambridge University Press
7. I, NumisWiki, The Collaborative Numismatics Project
8. Phonetic Extensions code chart (U+1D00), The Unicode Standard, Version 17.0
9. Chapter 7, The Unicode Standard, Version 18.0.0
10. Sorting IJ in the Netherlands, SC22/WG20 N865
11. U+0049 Latin Capital Letter I, Codepoints

Topic: Encyclopedia › Society and history › Languages and linguistics › Writing and notation systems › Latin script

Initially written Sep 17, 2026 · Reviewed: Oct 25, 2026 · Edited: Oct 15, 2026; Oct 25, 2026 · Last review: Oct 25, 2026

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