|Egyptian hieroglyph ꜥ||Phoenician
In Semitic, the letter may have originated in a hieroglyph for an arm that represented a voiced pharyngeal fricative (/ʕ/) in Egyptian, but was reassigned to /j/ (as in English "yes") by Semites, because their word for "arm" began with that sound. This letter could also be used to represent /i/, the close front unrounded vowel, mainly in foreign words.
The Greeks adopted a form of this Phoenician yodh as their letter iota (⟨Ι, ι⟩) to represent /i/, the same as in the Old Italic alphabet. In Latin (as in Modern Greek), it was also used to represent /j/. The modern letter 'j' was firstly a variation of 'i', and both were used interchangeably for both the vowel and the consonant, coming to be differentiated only in the 16th century. The dot over the lowercase 'i' is sometimes called a tittle. In the Turkish alphabet, dotted and dotless I are considered separate letters, representing a front and back vowel, respectively, and both have uppercase ('I', 'İ') and lowercase ('ı', 'i') forms.
In modern English, 'i' represents different sounds, either a "long" diphthong /aɪ/ as in kite, which developed from Middle English /iː/ after the Great Vowel Shift of the 15th century, or the "short" /ɪ/ as in bill.
In some san serif typefaces, the uppercase letter I, 'I' may be difficult to distinguish from the lowercase letter L, 'l', the vertical bar character '|', or the digit one '1'. In serifed typefaces, the capital form of the letter has both a baseline and a cap-height serif, while the lowercase L has generally a hooked ascender and a baseline serif.
The uppercase I does not have a dot (tittle) while the lowercase i has it in the most of Latin-based alphabet schemes. However, some schemes, such as the Turkish alphabet, have two kinds of I's: the dotted one (İi) and the dotless one (Iı).
The uppercase I has two kinds of shapes, which are one with crossbars () and without crossbars (). Usually, they are considered same, but they are distinguished in some extended Latin alphabet system such as the 1978 version of the African reference alphabet. In the system, the former is the uppercase counterpart of ɪ and the latter is the counterpart of 'i'.
Computing codes 
|Unicode name||LATIN CAPITAL LETTER I||LATIN SMALL LETTER I|
|Numeric character reference||I||I||i||i|
- 1 Also for encodings based on ASCII, including the DOS, Windows, ISO-8859 and Macintosh families of encodings.
Other representations 
See also 
Related letters and other similar characters 
- İ i and I ı : Latin dotted and dotless letter i
- І і : Cyrillic soft-dotted letter i
- И и : Cyrillic letter i
- Brown & Kiddle (1870) The institutes of English grammar, p. 19.
Ies is the plural of the English name of the letter; the plural of the letter itself is rendered I's, Is, i's, or is.
- Media related to I at Wikimedia Commons
- The dictionary definition of I at Wiktionary
- The dictionary definition of i at Wiktionary
Letter I with diacritics
|Í í||Ì ì||Ĭ ĭ||Î î||Ǐ ǐ||Ïï||Ḯḯ||Ĩĩ||Į į||Ī ī||Ỉ ỉ||Ȉ ȉ||Ȋ ȋ||Ị ị||Ḭ ḭ||Ɨ ɨ||ᵻ||ᶖ||İ i||I ı||ꟾ|