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 ''index Magazine'' was a New York City-based publication with interviews with art and culture figures. It was created by Peter Halley and Bob Nickas in 1996, running until late 2005. Covering the burgeoning indie culture of the 1990s, ''Index ...

'', 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 Henry Hotze (September 2, 1833 – April 19, 1887) was a Swiss American propagandist for the Confederate States of America during the American Civil War. He acted as a Confederate agent in Great Britain, attempting to build support for the Sout ...

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 rev ...

'', a student newspaper

Other arts, entertainment and media

* The Index (band) * ''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 a ...

* ''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 , formerly known as , is a Japanese corporate information and communications technology company owned by Sawada Holdings. "Index Corporation" was a corporate name used by three different Japanese companies, between 1997 and 2016, the last one be ...

, 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 the ...

, a statistical average of prices of selected securities

Places in the United States

* Index, Arkansas, an unincorporated community *

Index, Kentucky Index is an unincorporated community in Morgan County, Kentucky Kentucky ( , ), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders I ...

, 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 Off ...

, 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 Susqu ...

, 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 town *

Index, West Virginia Index is an unincorporated community in Gilmer County, West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers ...

, 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 Hebr ...

* The ''Index'', colloquial name for ''Germany's List of Media Harmful to Young People'', published by the

Bundesprüfstelle für jugendgefährdende Medien The Federal Department for Media Harmful to Young Persons (german: link=no, Bundesprüfstelle für jugendgefährdende Medien or ''BPjM'') is an upper-level German federal censorship agency subordinate to the Federal Ministry of Family Affai ...

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 ...

, 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 forbidd ...

'', 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 Subject indexing is the act of describing or classifying a document by index terms, keywords, or other symbols in order to indicate what different documents are ''about'', to summarize their contents or to increase findability. In other words, i ...

, 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 entries s ...

, 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 metadat ...

, 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, an ...

Array index In computer science, an array is a data structure consisting of a collection of ''elements'' (values or variables), each identified by at least one ''array index'' or ''key''. An array is stored such that the position of each element can be co ...

, 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 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 An index register in a computer's CPU is a processor register (or an assigned memory location) used for pointing to operand addresses during the run of a program. It is useful for stepping through strings and arrays. It can also be used for ho ...

, 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 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 When an HTTP client (generally a web browser) requests a URL that points to a directory structure instead of an actual web page within the directory structure, the web server will generally serve a default page, which is often referred to as a m ...

, 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, an ...

, 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, whe ...

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 consis ...

* 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 pr ...

, 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 tu ...

of an oriented closed curve on a surface relative to a point on that surface *

Diversity index A diversity index is a quantitative measure that reflects how many different types (such as species) there are in a dataset (a community), and that can simultaneously take into account the phylogenetic relations among the individuals distributed a ...

, 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' ...

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 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 in ...

, 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 o ...

, in linguistics, the phenomenon of a sign pointing to some object in the context in which it occurs *

Indexing (motion) Indexing in reference to motion is moving (or being moved) into a new position or location quickly and easily but also precisely. When indexing a machine part, its new location is known to within a few hundredths of a millimeter (thousandths of an i ...

, 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, o ...

, a measurement of how light propagates through a material * Valve Index, 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 (p ...

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