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, a Croatian online newspaper * index.hu, 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'', a student newspaper

Other arts, entertainment and media

* The Index (band) * ''Indexed'', a Web cartoon by Jessica Hagy * ''Index'', album by

Ana Mena Ana Mena Rojas (born 25 February 1997) is a Spanish singer and actress. She began her career in 2009 in the TV series ''Marisol, la película'' (2009). In 2010, she participated in Disney The Walt Disney Company, commonly known as Disney ...

Business enterprises and events

Index (retailer) Index was a catalogue retailer in the United Kingdom, that was owned by Littlewoods Littlewoods was a retail and football betting company founded in Liverpool, England, by John Moores in 1923. By the 1980s, it had grown to become the la ...

, 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, avai ...

, 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 th ...

, 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, a ghost town *

Index, New York Index is a hamlet in the Town of Hartwick, New York, and partially in Town of Otsego, Otsego County, New York, United States. It is located at the corner of CR-11 and NY-28. Oaks Creek runs east through the hamlet and converges with the Sus ...

, 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 a ...

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

Publishing and library studies

Bibliographic index A bibliographic index is a bibliography intended to help find a publication. Citations are usually listed by author and subject in separate sections, or in a single alphabetical sequence under a system of authorized headings collectively known as ...

, a regularly updated publication that lists articles, books, or other information items *

Citation index A citation index is a kind of bibliographic index, an index of citations between publications, allowing the user to easily establish which later documents cite which earlier documents. A form of citation index is first found in 12th-century Hebre ...

* 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 forbid ...

'', 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) The manicule, , is a typographic mark with the appearance of a hand with its index finger extending in a pointing gesture. Originally used for handwritten marginal notes, it later came to be used in printed works to draw the reader's attentio ...

, a hand- or fist-shaped punctuation mark * Subject indexing, describing the content of a document by keywords * Thumb index, a round cut-out in the pages of a publication *

Web indexing Web indexing, or internet indexing, comprises methods for indexing the contents of a website or of the Internet as a whole. Individual websites or intranets may use a back-of-the-book index, while search engines usually use keywords and metadata t ...

, Internet indexing

Science, technology, and mathematics

Computer science

* Index, a key in an

associative array In computer science, an associative array, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In mathematical terms an ...

, a character in Unicode, its code is 132 * Index, the dataset maintained by

search engine indexing Search engine indexing is the collecting, parsing, and storing of data to facilitate fast and accurate information retrieval. Index design incorporates interdisciplinary concepts from linguistics, cognitive psychology, mathematics, informatics, and ...

* Array index, an integer pointer into an array data structure * BitTorrent index, a list of .torrent files available for searches *

Database index A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure. Indexes are used to quickly locate data without ...

, a data structure that improves the speed of data retrieval * Index mapping 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), 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 w ...

, a data structure used to store precomputed information *

Site map A sitemap is a list of pages of a web site within a domain. There are three primary kinds of sitemap: * Sitemaps used during the planning of a website by its designers. * Human-visible listings, typically hierarchical, of the pages on a site. * S ...

, or site index, a list of pages of a web site accessible to crawlers or users *

, 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 In mathematics, a family, or indexed family, is informally a collection of objects, each associated with an index from some index set. For example, a ''family of real numbers, indexed by the set of integers'' is a collection of real numbers, wher ...

or set * Index, an element of an

index set In mathematics, an index set is a set whose members label (or index) members of another set. For instance, if the elements of a set may be ''indexed'' or ''labeled'' by means of the elements of a set , then is an index set. The indexing consists ...

* Index, the label of a summand in Σ-notation of a summation

Algebra

Index of a subgroup In mathematics, specifically group theory, the index of a subgroup ''H'' in a group ''G'' is the number of left cosets of ''H'' in ''G'', or equivalently, the number of right cosets of ''H'' in ''G''. The index is denoted , G:H, or :H/math> or ( ...

, 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 mapping V \to W between two vector spaces that ...

, 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'' (franchi ...

* 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 ...

Analysis

* Index, the

winding number In mathematics, the winding number or winding index of a closed curve in the plane around a given point is an integer representing the total number of times that curve travels counterclockwise around the point, i.e., the curve's number of t ...

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 a ...

, 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, 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, ...

, 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 satellite * Index:, a Danish nonprofit organization which promotes Design for Life *

The Index (Dubai) The Index is a tall, 80-storey skyscraper in Dubai, United Arab Emirates. Of the 80 floors, the first four floors are service floors, 5th–29th are to be offices and 31st–77th are residential use, 73rd and 75th floors are duplex penthouses and ...

, a skyscraper * Index (crater), a moon crater