I is the ninth letter in the Latin alphabet, derived from the Greek iota (Ι, ι). It stood for the vowel /i/, the same as in the Etruscan alphabet. In Latin (as in Modern Greek) /j/ (as English Y in YOKE) was added. In Semitic, /j/ was the usual sound value of Jôd (probably originally a pictogram for an arm with hand), /i/ only in foreign words. In English, I represents different sounds, among them a diphthong that developed fro/ as well as short, open / as in BILL. The dot over the lowercase 'i' is called a tittle.
In the NATO phonetic alphabet I is represented by India, or more rarely, Indigo.
In context, I is also:
- A word: the pronoun "I" that is used in the English language by a person to refer to himself or herself.
- In chemistry, a symbol for the chemical element iodine.
- In mathematics, the letter i is used for the imaginary unit, a complex number whose square is -1.
- In physics, the variable I for current. The imaginary unit is represented by j instead.
- A symbol (I) for the closed unit interval, that is all real numbers from 0 to 1 inclusive, and also for the identity matrix.
- The Roman numeral for one, whether uppercase or lowercase.
- A Swedish film made in 1966, see I.
- In the Turkish alphabet, "I" and "i" are different letters.