I

Look up I in Wiktionary, the free dictionary.

I is the ninth letter of the Latin alphabet.

I or i can also refer to:

• the Close front unrounded vowel in the International Phonetic Alphabet and many other Latin-based orthographies
• I (pronoun), the first-person singular pronoun in English

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
• (pronounced "i-hat"), the unit vector along the x-axis in Cartesian coordinates

Music

• I, a diatonic function in tonal music theory
• I (Kurt Nilsen album)
• I (The Magnetic Fields album)
• I (Cilvaringz album)
• I (Die Krupps album)
• I (JonnyX and the Groadies album)
• i (Misako Odani album)
• I (Nightingale album)
• I (band), a band formed by members of Immortal, Enslaved, Gorgoroth, and Sahg
• I (EP), an EP by Meshuggah
• "I" (Aphex Twin song)
• "I", a song on Dehumanizer, an album by Black Sabbath
• "I", a song on Weather Systems, an album by Andrew Bird
• "I", a song on Coal Chamber, an album by Coal Chamber
• "I", a song on Music from "The Elder", an album by KISS
• "I", a song on Eternal, an album by Samael

Physics

• I and i, symbols for electric current signals in electronic engineering
• I, the moment of inertia
• I, symbol for the luminous intensity

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

Miscellania

• I, a character in Adventure into Fear who acted as a guide for Morbius, the Living Vampire
• I, the symbol for Italy in the list of international license plate codes
• I, the registration prefix for Italy in aircraft registrations
• Goddess I, a Mayan deity
• /i/, /ɨ/ and /ɪ/, in the International Phonetic Alphabet, the three forms of the letter I
• I (kana), one of the Japanese kana that each represent one mora
• IBM i is a computer operating system.
• Lowercase i prefix, a common prefix used by Internet and electronic companies
• Mitsubishi i, a Japanese kei car
• Individual-i, a symbol promoted by Bruce Schneier

This disambiguation page lists articles associated with the same Latin letter. If an internal link led you here, you may wish to change the link to point directly to the intended article.