I is the ninth letter of the Latin alphabet. I or i may also refer to:

Language

I (pronoun) In Modern English, ''I'' is the singular, first-person pronoun. Morphology In Standard Modern English, ''I'' has five distinct word forms: * ''I'': the nominative (subjective) form **''I'' is the only pronoun form that is always capital ...

, the first-person singular subject pronoun in English *

I (Cyrillic) I (И и; italics: ''И и'' or ; italics: ) is a letter used in almost all modern Cyrillic alphabets with the exception of Belarusian alphabet, Belarusian. It commonly represents either the close front unrounded vowel (e.g., ...

, a letter used in almost all ancient and modern Cyrillic alphabets * ı,

dotless I I, or ı, called dotless i, is a letter used in the Latin-script alphabets of Azerbaijani, Crimean Tatar, Gagauz, Kazakh, Tatar and Turkish. It commonly represents the close back unrounded vowel , except in Kazakh where it represents the ...

, letter used in Turkish and Azerbaijani * i,

close front unrounded vowel The close front unrounded vowel, or high front unrounded vowel, is a type of vowel sound that occurs in most spoken languages, represented in the International Phonetic Alphabet by the symbol i. It is similar to the vowel sound in the Englis ...

, in the International Phonetic Alphabet * ɨ,

close central unrounded vowel The close central unrounded vowel, or high central unrounded vowel, is a type of vowel sound used in some languages. The symbol in the International Phonetic Alphabet that represents this sound is , namely the lower-case I, letter ''i'' with ...

, in the International Phonetic Alphabet * ɪ,

near-close near-front unrounded vowel The near-close near-front unrounded vowel, or near-high near-front unrounded vowel, is a type of vowel sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is , the small capital ...

, in the International Phonetic Alphabet *

I (kana) I (い in hiragana or イ in katakana) is one of the Japanese kana each of which represents one mora. い is based on the sōsho style of the kanji character 以, and イ is from the radical (left part) of the kanji character 伊. In the mode ...

, one of the Japanese kana that each represent one mora * I, male prefix to some

Balinese name A Balinese name is part of a system of identification used by the Balinese people and in the western parts of the neighboring island of Lombok, Indonesia. A Balinese name will have three parts: a title, a birth order name and a personal name. Bali ...

Science, technology, and mathematics

Biology

Troponin I Troponin I is a cardiac and skeletal muscle protein family. It is a part of the troponin protein complex, where it binds to actin in thin myofilaments to hold the actin-tropomyosin complex in place. Troponin I prevents myosin from binding to act ...

, one of the three

troponin Troponin, or the troponin complex, is a complex of three regulatory proteins (troponin C, troponin I, and troponin T) that are integral to muscle contraction in skeletal muscle and cardiac muscle, but not smooth muscle. Measurements of cardiac-spe ...

s *

Haplogroup I (mtDNA) Haplogroup I is a human mitochondrial DNA (mtDNA) haplogroup. It is believed to have originated about 21,000 years ago, during the Last Glacial Maximum (LGM) period in West Asia ; ; ). The haplogroup is unusual in that it is now widely distribut ...

, a human mitochondrial DNA (mtDNA) haplogroup *

Haplogroup I (Y-DNA) Haplogroup I (M170) is a Y-chromosome DNA haplogroup. It is a subgroup of haplogroup IJ, which itself is a derivative of the haplogroup IJK. Subclades I1 and I2 can be found in most present-day European populations, with peaks in some Nort ...

, a Y-chromosomal DNA (Y-DNA) haplogroup *

Olfactory nerve The olfactory nerve, also known as the first cranial nerve, cranial nerve I, or simply CN I, is a cranial nerve that contains sensory nerve fibers relating to the sense of smell. The afferent nerve fibers of the olfactory receptor neurons t ...

, the 1st cranial nerve in human anatomy * the Lợn Ỉ or Vietnamese Pot-bellied pig

Chemistry

Iodine Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...

, symbol I, a chemical element * I,

isoleucine Isoleucine (symbol Ile or I) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form under biological conditions), an α-carboxylic acid group (which is in the depro ...

, an amino acid * I,

ionic strength The ionic strength of a solution is a measure of the concentration of ions in that solution. Ionic compounds, when dissolved in water, dissociate into ions. The total electrolyte concentration in solution will affect important properties such a ...

in a chemical solution * ,

Van 't Hoff factor The van 't Hoff factor (named after Dutch chemist Jacobus Henricus van 't Hoff) is a measure of the effect of a solute on colligative properties such as osmotic pressure, relative lowering in vapor pressure, boiling-point elevation and freez ...

Computing

* i, a common generic index variable often used in

program loops In computer science, control flow (or flow of control) is the order in which individual statements, instructions or function calls of an imperative program are executed or evaluated. The emphasis on explicit control flow distinguishes an ''im ...

* <i>, an

HTML element An HTML element is a type of HTML (HyperText Markup Language) document component, one of several types of HTML nodes (there are also text nodes, comment nodes and others). The first used version of HTML was written by Tim Berners-Lee in 199 ...

for marking italic type * .i, the common filename extension for a file that contains the output from a

preprocessor In computer science, a preprocessor (or precompiler) is a Computer program, program that processes its input data to produce output that is used as input in another program. The output is said to be a preprocessed form of the input data, which i ...

* i-, a prefix for

Apple An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...

products and services e.g. iMac, iPod, iPhone, iCloud * i-, an

Internet-related prefix Internet-related prefixes such as ''wikt:e-, e-'', ''wikt:i-, i-'', ''wikt:cyber-, cyber-'', ''wikt:info-, info-'', ''wikt:techno-, techno-'' and ''wikt:net-, net-'' are added to a wide range of existing words to describe new, Internet- or computer ...

used by Internet and electronic companies

Mathematics

* I, the

Roman numeral Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, ea ...

for 1 * ,

imaginary unit The imaginary unit or unit imaginary number () is a mathematical constant that is a solution to the quadratic equation Although there is no real number with this property, can be used to extend the real numbers to what are called complex num ...

, for which * or ,

identity matrix In linear algebra, the identity matrix of size n is the n\times n square matrix with ones on the main diagonal and zeros elsewhere. It has unique properties, for example when the identity matrix represents a geometric transformation, the obje ...

of indeterminate size (or of size ) * ,

unit interval In mathematics, the unit interval is the closed interval , that is, the set of all real numbers that are greater than or equal to 0 and less than or equal to 1. It is often denoted ' (capital letter ). In addition to its role in real analysi ...

, which contains all real numbers from 0 to 1 inclusive * , an index variable, e. g. in a

matrix Matrix (: matrices or matrixes) or MATRIX may refer to: Science and mathematics * Matrix (mathematics), a rectangular array of numbers, symbols or expressions * Matrix (logic), part of a formula in prenex normal form * Matrix (biology), the m ...

or for

summation In mathematics, summation is the addition of a sequence of numbers, called ''addends'' or ''summands''; the result is their ''sum'' or ''total''. Beside numbers, other types of values can be summed as well: functions, vectors, matrices, pol ...

* , the

regularized incomplete beta function In mathematics, the beta function, also called the Euler integral of the first kind, is a special function that is closely related to the gamma function and to binomial coefficients. It is defined by the integral : \Beta(z_1,z_2) = \int_0^1 t^( ...

(of a variable and parameters ) * , the

unit vector In mathematics, a unit vector in a normed vector space is a Vector (mathematics and physics), vector (often a vector (geometry), spatial vector) of Norm (mathematics), length 1. A unit vector is often denoted by a lowercase letter with a circumfle ...

along the ''x''-axis in Cartesian coordinates

Physics and astronomy

* , ,

electric current An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge c ...

* ,

isospin In nuclear physics and particle physics, isospin (''I'') is a quantum number related to the up- and down quark content of the particle. Isospin is also known as isobaric spin or isotopic spin. Isospin symmetry is a subset of the flavour symmetr ...

* ,

luminous intensity In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the huma ...

* ,

moment of inertia The moment of inertia, otherwise known as the mass moment of inertia, angular/rotational mass, second moment of mass, or most accurately, rotational inertia, of a rigid body is defined relatively to a rotational axis. It is the ratio between ...

* ,

orbital inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Earth ...

* I (Roman number one), in the Yerkes spectral classification scheme, the symbol for supergiants

Telecommunication

I band (NATO) The NATO I band is the obsolete designation given to the radio frequencies from 8,000 to 10,000 MHz (equivalent to wavelengths between 3.75 and 3 cm) during the Cold War The Cold War was a period of global Geopolitics, geopol ...

, the range of radio frequencies from 8 GHz to 10 GHz in the electromagnetic spectrum * I, the

ITU prefix The International Telecommunication Union (ITU) allocates call sign prefixes for radio and television stations of all types. They also form the basis for, but may not exactly match, aircraft registration identifiers. These prefixes are agreed upo ...

allocated to Italy in radio communication * I, in

QAM Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message sign ...

modulation schemes, the in-phase communications channel

Other uses in technology

* i, a suffix unit for

video resolution The display resolution or display modes of a digital television, computer monitor, or other display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resoluti ...

(vertical Interlaced lines), as in 480i or 1080i * ''I'', in the

YIQ YIQ is the color space used by the analog NTSC color TV system. ''I'' stands for ''in-phase'', while ''Q'' stands for ''quadrature'', referring to the components used in quadrature amplitude modulation. Other TV systems used different color spa ...

colorspace commonly used with the NTSC television encoding scheme, the color-difference channel which is in-phase with the subcarrier

Arts and media

Music

I (band) I were a Norwegian black metal supergroup formed in 2003. The band featured Immortal frontman Abbath, Enslaved guitarist Ice Dale, Gorgoroth bassist TC King and former Immortal drummer Armagedda. I released their debut studio album, '' Betw ...

, a Norwegian heavy metal band * I, a

diatonic function In music, function (also referred to as harmonic function) is a term used to denote the relationship of a chord"Function", unsigned article, ''Grove Music Online'', . or a scale degree to a tonal centre. Two main theories of tonal functions exist ...

in tonal music theory

Albums

* ''i'' (A.R. Kane album), 1989 * ''I'' (Ben Lester album), 2019 * ''I'' (Cilvaringz album), 2007 * ''I'' (Cursed album), 2003 * ''I'' (Die Krupps album), 1992 * ''I'' (Felix Jaehn album), 2018 * ''I'' (Ikimono-gakari album), 2013 * I (Imminence album), 2014 * ''I'' (Jaejoong EP), 2013 * ''I'' (Juju album), 2018 * ''I'' (Kingston Wall album), 1992 * ''I'' (Kurt Nilsen album), 2003 * ''i'' (The Magnetic Fields album), 2004 * ''I'' (Meshuggah EP), 2004 * ''i'' (Misako Odani album), 1997 * ''I'' (Nightingale album), 2000 * ''I'' (Sahg album), 2006 * ''I'' (Taeyeon EP), 2015 * ''I'' (Xerath album), 2009 * ''I'' (soundtrack), by A. R. Rahman from the eponymous 2015 film * ''I.'', a 2012 EP by Cigarettes After Sex

Songs

* "i" (Kendrick Lamar song), a 2014 song by Kendrick Lamar from his album ''To Pimp a Butterfly'' * "i" (Lil Skies song), a song 2019 by Lil Skies from his debut album ''Shelby'' * "I" (Taproot song), a 2001 song by band Taproot from their album ''Gift'' * "

I (Who Have Nothing) "I (Who Have Nothing)" (sometimes billed as "I Who Have Nothing") is an English-language cover of the Italian song "''Uno dei tanti''" (English: "One of Many"), with music by Carlo Donida and lyrics by Giulio "Mogol" Rapetti. The original vers ...

", a 1966 Ben. E. King song also recorded by Tom Jones, who used the title for one of his albums * "I", a 2003 song on '' Weather Systems'', an album by Andrew Bird * "I", a 1992 song on ''

Selected Ambient Works 85–92 ''Selected Ambient Works 85–92'' is the debut studio album by the British electronic music artist and producer Richard D. James under the alias of Aphex Twin. It was released on 9November 1992 through Apollo Records, a subsidiary of the Bel ...

'', an album by Aphex Twin * "I", a 1992 song on '' Dehumanizer'', an album by Black Sabbath * "I", a 1997 song on ''

Coal Chamber Coal Chamber is an American nu metal band formed by Dez Fafara and Meegs Rascón in Los Angeles in 1992, initially under the name She's in Pain. The original lineup also consisted of bassist Rayna Foss and drummer Jon Tor. Mike Cox replaced Tor ...

'', an album by Coal Chamber * "I", a 1967 song on '' Underground'', an album by The Electric Prunes * "I", a 2012 song on ''

Muse In ancient Greek religion and Greek mythology, mythology, the Muses (, ) were the Artistic inspiration, inspirational goddesses of literature, science, and the arts. They were considered the source of the knowledge embodied in the poetry, lyric p ...

'', an album by Jolin Tsai * "I", a 1981 song on ''

Music from "The Elder" ''Music from "The Elder"'' is the ninth studio album by American rock band Kiss, released on November 10, 1981 by Casablanca Records. The album marked a substantial departure from their previous output with the concept and orchestral elements. It ...

'', an album by Kiss * "I", a 1994 song on ''

Made in USA A Made in USA mark is a country of origin label affixed to American-made products that indicates the product is "all or virtually all" domestically produced, manufactured and assembled in the United States. The label is regulated by the Federal ...

'', an album by Pizzicato Five * "I", a 1999 song on ''

Eternal Eternal(s) or The Eternal may refer to: * Eternity, an infinite amount of time, or a timeless state * Immortality or eternal life * God, the supreme being, creator deity, and principal object of faith in monotheism Comics, film and television * ...

'', an album by Samael * "I", a 2003 song on '' Winter Story'', an album by Shinhwa * "I", a 2008 song on '' In the Shadow of a Thousand Suns'', an album by Abigail Williams * "I", a 2011 song on '' Cinderella's Eyes'', an album by Nicola Roberts * "I", a 2015 song on '' I'', an EP by Taeyeon * "I", a 2016 song by Rezz * "I", a 2019 song by

Hey! Say! JUMP Hey! Say! JUMP (HSJ or JUMP) is an nine-member Japanese boy band under the Japanese talent agency Smile-Up (formerly known as Johnny & Associates). The group is split into two sub-groups: Hey! Say! BEST and Hey! Say! 7. In Japan they sold more ...

Other media

* ''I'' (2015 film), an Indian Tamil-language film * ''I'' (2016 film), an Iranian film * i (TV network), the former name of ION Television * ''

The i Paper ''The i Paper'', known as ''i'' until December 2024, is a British national newspaper published in London by Daily Mail and General Trust and distributed across the United Kingdom. It is aimed at "readers and lapsed readers" of all ages and c ...

'', a British newspaper, formerly known as ''i'' * ''i'' (Portuguese newspaper), a Portuguese newspaper based in Lisbon * I, a character in the comic book series '' Adventure into Fear'' * '' "I" Is for Innocent'', the ninth novel in Sue Grafton's "Alphabet mystery" series, published in 1992 * ''

I, a Man ''I, a Man'' is a 1967 American erotic drama film written, directed and filmed by Andy Warhol. It debuted at the Hudson Theatre in New York City on August 25, 1967. The film depicts the main character, played by Tom Baker, in a series of sexual ...

'', a 1967 Andy Warhol film

Mythology

Goddess I Goddess I is the Taube's Schellhas-Zimmermann letter designation for one of the most important Maya deities: a youthful woman to whom considerable parts of the post-Classic codices are dedicated, and who equally figures in Classic Period scenes. ...

, a Mayan deity * Hou-i, or I, a heroic archer and hunter in Chinese mythology

Vehicles and transportation

* Italy (I), in the

list of international vehicle registration codes The country in which a motor vehicle's vehicle registration plate was issued may be indicated by an international vehicle registration code, also called Vehicle Registration Identification code or VRI code, formerly known as an Internationa ...

* Italy (

aircraft registration An aircraft registration is a code unique to a single aircraft, required by international convention to be marked on the exterior of every civil aircraft. The registration indicates the aircraft's country of registration, and functions much li ...

prefix) *

Mitsubishi i The is a kei car from automaker Mitsubishi Motors, first released in January 2006, twenty eight months after its debut at the Frankfurt Motor Show#2003, 2003 Frankfurt Motor Show. It is the first four-door automobile since the 1960s to employ ...

, a Japanese kei car * I (Los Angeles Railway), a former streetcar line in Los Angeles *

Toei Mita Line The is a rapid transit, subway line of the municipal Toei Subway network in Tokyo, Japan. The line runs between Nishi-Takashimadaira Station, Nishi-Takashimadaira in Itabashi, Tokyo, Itabashi and Meguro Station, Meguro in Shinagawa, Tokyo, Shi ...

, a subway service operated by the Tokyo Metropolitan Bureau of Transportation (Toei), labeled Toei Mita line symbol

Imazatosuji Line The is a rapid transit line of Osaka Metro, running from Itakano Station in Higashiyodogawa-ku to Imazato Station in Higashinari-ku, all within Osaka city. Its official name is , and in MLIT publications, it is written as . Station numbers ...

, a subway service operated by the Osaka Metro, labeled Osaka Metro Imazatosuji line symbol

, the official West Japan Railway Company service symbol for the

Kakogawa Line The is a railway line in Hyōgo Prefecture, Japan, operated by West Japan Railway Company (JR West), which connects the cities of Kakogawa and Tamba. The line begins at Kakogawa Station on the JR Kobe Line (Sanyō Main Line) and ends at Tan ...

Other uses

* i, an international symbol for visitor or tourist information; see

ISO 7001 ISO 7001 ("public information symbols") is a standard published by the International Organization for Standardization that defines a set of pictograms and symbols for public information. The latest version, ISO 7001:2023, was published in Februar ...

Nintendo DSi The is a foldable dual-screen handheld game console released by Nintendo. The console launched in Japan on November 1, 2008, and worldwide beginning in April 2009. It is the third iteration of the Nintendo DS, and its primary market rival was ...

, the third model in the Nintendo DS line, released in 2008 *

Nintendo DSi XL The is a foldable dual-screen handheld game console released by Nintendo. The console launched in Japan on November 1, 2008, and worldwide beginning in April 2009. It is the third iteration of the Nintendo DS, and its primary market rival was ...

, the larger version of the DSi, released in 2009 * I, an alternative romanization of

Lee (Korean surname) Lee, I, or Yi () is the List of Korean surnames, second-most-common surname in Korea, behind Kim (Korean surname), Kim (). As of the South Korean census of 2015, there were 7,306,828 people by this name in South Korea or 14.7% of the populatio ...

I-Foundation Avanti Schools Trust is the sponsor of state-funded Hindu faith schools in the United Kingdom. The I-Foundation is a Hindu and ISKCON charity in England and Wales that is the religion, religious authority governing schools run by the Avanti Sch ...

, a charity in charge of state-funded Hindu faith schools in the United Kingdom *

Interest rate An interest rate is the amount of interest due per period, as a proportion of the amount lent, deposited, or borrowed (called the principal sum). The total interest on an amount lent or borrowed depends on the principal sum, the interest rate, ...

(i), in economics *

Investment Investment is traditionally defined as the "commitment of resources into something expected to gain value over time". If an investment involves money, then it can be defined as a "commitment of money to receive more money later". From a broade ...

(I), in economics *

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

, the military time zone code for UTC+09:00