Index (or its plural form indices) may refer to:

Arts, entertainment, and media

Fictional entities

* Index (''A Certain Magical Index''), a character in the light novel series ''A Certain Magical Index'' * The Index, an item on a Halo megastructure in the ''Halo'' series of video games

Periodicals and news portals

* '' Index Magazine'', a publication for art and culture *

Index.hr Index.hr is a Croatian tabloid online newspaper, launched in December 2002 and based in Zagreb. It was founded by Matija Babić and was originally designed as a news aggregation website, providing news content from Croatia, Serbia and Bosnia ...

, a Croatian online newspaper *

index.hu Index.hu is a Hungarian news website covering both Hungarian and international news. In 2018, it was the most visited Hungarian website with an average of 1.5 million daily readers. While most of the website's articles are written in Hungarian, ...

, a Hungarian-language news and community portal * ''The Index'' (Kalamazoo College), a student newspaper * ''The Index'', an 1860s European propaganda journal created by Henry Hotze to support the Confederate States of America * ''

Truman State University Index The ''Truman State University Index'' is a weekly student newspaper distributed at Truman State University and throughout the Kirksville, Missouri community. The publication is entirely student-run and funded mostly through its own advertising reve ...

'', a student newspaper

Other arts, entertainment and media

The Index (band) The Index were an American garage rock/psychedelic rock band from Grosse Pointe, Michigan who were active from 1966-1969 and are known for a sound characterized by droning guitars, as heard on their two albums, both released in 1968. Though they ...

* ''Indexed'', a Web cartoon by

Jessica Hagy Jessica Hagy is known for the online cartoon Indexed which is a collection of charts and diagrams hand drawn on 3x5 index cards and organized into a blog format. She has compiled her cartoons into a book called ''Indexed''. The cartoon has also ...

* ''Index'', album by Ana Mena

Business enterprises and events

* Index (retailer), a former UK catalogue retailer *

INDEX Index (or its plural form indices) may refer to: Arts, entertainment, and media Fictional entities * Index (''A Certain Magical Index''), a character in the light novel series ''A Certain Magical Index'' * The Index, an item on a Halo megastru ...

, a market research fair in Lucknow, India * Index Corporation, a Japanese video game developer

Finance

Index fund An index fund (also index tracker) is a mutual fund or exchange-traded fund (ETF) designed to follow certain preset rules so that the fund can a specified basket of underlying investments.Reasonable Investor(s), Boston University Law Review, avail ...

, a collective investment scheme *

Stock market index In finance, a stock index, or stock market index, is an index that measures a stock market, or a subset of the stock market, that helps investors compare current stock price levels with past prices to calculate market performance. Two of the ...

, a statistical average of prices of selected securities

Places in the United States

* Index, Arkansas, an unincorporated community * Index, Kentucky, an unincorporated community *

Index, Missouri Index is an extinct town in Cass County, in the U.S. state of Missouri. Index was plat In the United States, a plat ( or ) (plan) is a cadastral map, drawn to scale, showing the divisions of a piece of land. United States General Land Of ...

, a ghost town *

Index, New York Index is a hamlet in the Hartwick, New York, Town of Hartwick, New York, and partially in Otsego, New York, Town of Otsego, Otsego County, New York, Otsego County, New York, United States. It is located at the corner of List of county routes in O ...

, a hamlet in Hartwick and Otsego, New York * Index, Virginia, an unincorporated community *

Index, Washington Index is a town in Snohomish County, Washington, United States. The population was 178 at the 2010 census. History Prior to settlement by White Americans, the Skykomish lived in the area between Sultan and Index. The Skykomish had a village al ...

, a town * Index, West Virginia, an unincorporated community

Publishing and library studies

* Bibliographic index, a regularly updated publication that lists articles, books, or other information items * Citation index * The ''Index'', colloquial name for ''Germany's List of Media Harmful to Young People'', published by the Bundesprüfstelle für jugendgefährdende Medien *

Index card An index card (or record card in British English and system cards in Australian English) consists of card stock (heavy paper) cut to a standard size, used for recording and storing small amounts of discrete data. A collection of such cards e ...

, used for recording and storing small amounts of data * ''

Index Librorum Prohibitorum The ''Index Librorum Prohibitorum'' ("List of Prohibited Books") was a list of publications deemed heretical or contrary to morality by the Sacred Congregation of the Index (a former Dicastery of the Roman Curia), and Catholics were forbidden ...

'', a list of publications which the Catholic Church censored *

Index on Censorship Index on Censorship is an organization campaigning for freedom of expression, which produces a quarterly magazine of the same name from London. It is directed by the non-profit-making Writers and Scholars International, Ltd (WSI) in association w ...

, a publishing organization that campaigns for freedom of expression, or its magazine of the same name *

Index (publishing) An index (plural: usually indexes, more rarely indices; see below) is a list of words or phrases ('headings') and associated pointers ('locators') to where useful material relating to that heading can be found in a document or collection of doc ...

, an organized list of information in a publication * Index (typography), a hand- or fist-shaped punctuation mark * Subject indexing, describing the content of a document by keywords *

Thumb index A thumb index, also called a cut-in index or an index notch, is a round cut-out in the pages of dictionaries, encyclopedias, Bibles and other large religious books, and various sectioned, often alphabetic, reference works, used to locate entrie ...

, a round cut-out in the pages of a publication * Web indexing, Internet indexing

Science, technology, and mathematics

Computer science

* Index, a key in an associative array * Index (typography), a character in Unicode, its code is 132 * Index, the dataset maintained by search engine indexing * Array index, an integer pointer into an array data structure * BitTorrent index, a list of .torrent files available for searches * Database index, a data structure that improves the speed of data retrieval *

Index mapping Index mapping (or direct addressing, or a trivial hash function) in computer science describes using an array, in which each position corresponds to a key in the universe of possible values. The technique is most effective when the universe of keys ...

of raw data for an array * Index register, a processor register used for modifying operand addresses during the run of a program * Indexed color, in computer imagery *

Indexed Sequential Access Method ISAM (an acronym for indexed sequential access method) is a method for creating, maintaining, and manipulating computer files of data so that records can be retrieved sequentially or randomly by one or more keys. Indexes of key fields are mainta ...

(ISAM), used for indexing data for fast retrieval *

Lookup table In computer science, a lookup table (LUT) is an array that replaces runtime computation with a simpler array indexing operation. The process is termed as "direct addressing" and LUTs differ from hash tables in a way that, to retrieve a value v wi ...

, a data structure used to store precomputed information * Site map, or site index, a list of pages of a web site accessible to crawlers or users * Web indexing, Internet indexing * Webserver directory index, a default or index web page in a directory on a web server, such as index.html

Economics

Index (economics) In Statistics, Economics and Finance, an index is a statistical measure of change in a representative group of individual data points. These data may be derived from any number of sources, including company performance, prices, productivity, and ...

, a single number calculated from an array of prices and quantities ** Price index, a typical price for some good or service

Mathematics and statistics

* Index, a number or other symbol that specifies an element of an indexed family or set * Index, an element of an index set * Index, the label of a summand in Σ-notation of a summation

Algebra

* Index of a subgroup, the number of a subgroup's left cosets * Index, the degree of an ''n''th root * Index of a

linear map In mathematics, and more specifically in linear algebra, a linear map (also called a linear mapping, linear transformation, vector space homomorphism, or in some contexts linear function) is a Map (mathematics), mapping V \to W between two vect ...

, the dimension of the map's kernel minus the dimension of its cokernel * Index of a

matrix Matrix most commonly refers to: * ''The Matrix'' (franchise), an American media franchise ** ''The Matrix'', a 1999 science-fiction action film ** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...

* Index of a real

quadratic form In mathematics, a quadratic form is a polynomial with terms all of degree two ("form" is another name for a homogeneous polynomial). For example, :4x^2 + 2xy - 3y^2 is a quadratic form in the variables and . The coefficients usually belong to a ...

Analysis

* Index, the winding number of an oriented closed curve on a surface relative to a point on that surface * Diversity index, a measure of distribution or variety in fields such as ecology or information science * Index of a vector field, an integer that helps to describe the behaviour of a vector field around an isolated zero

Number theory

* Index, or the

discrete logarithm In mathematics, for given real numbers ''a'' and ''b'', the logarithm log''b'' ''a'' is a number ''x'' such that . Analogously, in any group ''G'', powers ''b'k'' can be defined for all integers ''k'', and the discrete logarithm log''b' ...

of a number

Statistics

Index (statistics) In statistics and research design, an index is a composite statistic – a measure of changes in a representative group of individual data points, or in other words, a compound measure that aggregates multiple indicators. Indexes – also known as ...

, a type of aggregate measure **

Scale (social sciences) In the social sciences, scaling is the process of measuring or ordering entities with respect to quantitative attributes or traits. For example, a scaling technique might involve estimating individuals' levels of extraversion, or the perceived qual ...

, a method of reporting data in social sciences, sometimes called an index

Other uses in science and technology

Dental indices Tooth wear refers to loss of tooth substance by means other than dental caries. Tooth wear is a very common condition that occurs in approximately 97% of the population. This is a normal physiological process occurring throughout life; but with i ...

, standardized scoring systems for tooth problems *

Indexicality In semiotics, linguistics, anthropology, and philosophy of language, indexicality is the phenomenon of a ''sign'' pointing to (or ''indexing'') some object in the context in which it occurs. A sign that signifies indexically is called an index or, ...

, in linguistics, the phenomenon of a sign pointing to some object in the context in which it occurs * Indexing (motion), in mechanical engineering and machining, movement to a precisely known location *

Refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

, a measurement of how light propagates through a material *

Valve Index The Valve Index is a consumer virtual reality headset created and manufactured by Valve. Announced on April 30, 2019, the headset was released on June 28 of the same year. The Index is a second-generation headset and the first to be manufacture ...

, a virtual reality headset

Other uses

* ''INDEX'', earlier name for the

Reimei Reimei ('Dawn') is the in-flight name for a small Japanese satellite known during development as INDEX (INnovative-technology Demonstration Experiment), developed in-house at JAXA both to serve as a demonstration of small-satellite technologies ( ...

satellite * Index:, a Danish nonprofit organization which promotes Design for Life * The Index (Dubai), a skyscraper *

Index (crater) Index is a feature on Earth's Moon, a crater in the Hadley–Apennine region. Astronauts David Scott and James Irwin landed the Lunar Module ''Falcon'' northwest of it in 1971, on the Apollo 15 mission, but they did not visit it. They intended ...

, a moon crater