I (disambiguation)

I is the ninth letter of the alphabet. It can also refer to:

* I (pronoun), the first-person singular pronoun

Astronomy

* "i", the symbol for orbital inclination
* I, in the Yerkes spectral classification scheme the symbol for supergiants

Chemistry

* I, the symbol for iodine on the periodic table
* I, the symbol for isoleucine in biochemistry

Economics

* i, the symbol for the interest rate
* I, the symbol for investment

Genetics

* Haplogroup I (mtDNA), a human mitochondrial DNA (mtDNA) haplogroup
* Haplogroup I (Y-DNA), a Y-chromosomal DNA (Y-DNA) haplogroup

Mathematics

* 1 (number) in Roman numerals
* "i", the imaginary unit for which i² = -1 - "See also": "Imaginary number"
* "I" (or "I"_"n"), an identity matrix of indeterminate size (or of size "n")
* "i", an index variable in a matrix
* "I"_"x"("a","b"), the regularized incomplete beta function (of a variable "x" and parameters "a","b")
* "I", the closed unit interval which contains all real numbers from 0 to 1 inclusive
* $\{hat\{imath$ (pronounced "i-hat"), the unit vector along the x-axis in Cartesian coordinates

Music

* I, a diatonic function in tonal music theory
* "I" (album), the debut album of Kurt Nilsen
* I (band), a band formed by members of Immortal, Enslaved, Gorgoroth, and Sahg
* "I" (Cilvaringz album), the debut album of Wu-Tang Clan affiliate producer Cilvaringz
* "I" (EP), an EP by Meshuggah
* "I" (Magnetic Fields album), an album by the Magnetic Fields
* "I", a song on "Dehumanizer", an album by Black Sabbath
* "I", a song on "Coal Chamber", an album by Coal Chamber
* "I", a song on "Music from "The Elder"", an album by KISS

Physics

* "I" and "i", symbols for electric current signals in electronic engineering
* "I", the moment of inertia

Computer programming

* i, a common generic index variable often used for looping constructs
* <i>, an HTML element for marking italic type
* .i, the common filename extension for a file that contains the output from a preprocessor.

Radio and television

* i (TV network), the former name of ION Television
* I band, the range of radio frequencies from 8 GHz to 10 GHz in the electromagnetic spectrum
* I, the ITU prefix allocated to Italy in radio communication
* I, in QAM modulation schemes, the in-phase communications channel
* "I", in the YIQ colorspace commonly used with the NTSC television encoding scheme, the color-difference channel which is in-phase with the subcarrier

Miscellenea

* I (kana), one of the Japanese kana that each represent one mora
* I, the symbol for Italy in the list of international license plate codes
* /i/, IPA|/ɨ/ and IPA|/ɪ/, in the International Phonetic Alphabet, the three forms of the letter I
* Mitsubishi i, a Japanese "kei car"
* I, a character in Adventure into Fear who acted as a guide for Morbius, the Living Vampire
* Lowercase i prefix, a common prefix used by Internet and electronic companies
* IBM i is a computer operating system.

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