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 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 Henry Hotze (September 2, 1833 – April 19, 1887) was a Swiss Americans, 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 suppo ...

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) 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 * ''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, 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, a statistical average of prices of selected securities

Places in the United States

Index, Arkansas Index is an unincorporated community in Miller County, Arkansas Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the s ...

, 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, a ghost town * Index, New York, a hamlet in Hartwick and Otsego, New York *

Index, Virginia Index is an unincorporated community located in King George County, in the U. S. state of Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between t ...

, an unincorporated community * Index, Washington, 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 Hebre ...

* 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, used for recording and storing small amounts of data * '' Index Librorum Prohibitorum'', a list of publications which the Catholic Church censored * Index on Censorship, a publishing organization that campaigns for freedom of expression, or its magazine of the same name * Index (publishing), 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 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 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 hol ...

, a processor register used for modifying operand addresses during the run of a program *

Indexed color In computing, indexed color is a technique to manage digital images' colors in a limited fashion, in order to save computer memory and file storage, while speeding up display refresh and file transfers. It is a form of vector quantization comp ...

, 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 key (computing), keys. Indexes of key ...

(ISAM), used for indexing data for fast retrieval * Lookup table, 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), 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 pr ...

, the dimension of the map's kernel minus the dimension of its cokernel * Index of a matrix * Index of a real quadratic form

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 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 of a number

Statistics

* Index (statistics), 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 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, 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 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