Index

An index is an indirect shortcut derived from and pointing into a greater volume of values, data, information or knowledge. Index may refer to:

Business

• Index Corporation, a Japanese video game developer
• INDEX, a market research fair in Lucknow, India
• Index fund, a collective investment scheme
• Stock market index, a statistical average of prices of selected securities

Publishing

• Bibliographic index, a regularly updated print periodical publication that lists articles, books, and/or other information items, usually within a particular discipline
• Citation index
• Index (publishing), a detailed list, usually arranged alphabetically, of the specific information in a publication
• Index (typography), a (rare today) punctuation mark
• Index cards in a rolodex, an old library card catalog or other organizational purpose, usually but not always 3" x 5", early and mid-20th century technologies for maintaining list of information, and in the card catalog also useful for cross-referencing information
• Germany's List of Media Harmful to Young People, colloquially known as The Index, published by the Bundesprüfstelle für jugendgefährdende Medien
• Index Librorum Prohibitorum, a list of publications which the Catholic Church censored (translates loosely from Latin as : "Banned Book List")
• Index Librorum Prohibitorum, a character from the Japanese light novel, anime and manga A Certain Magical Index. "Index" may refer either to the character or the series
• Index Magazine, a New York City-based publication for art and culture
• Index on Censorship, a publishing organization that campaigns for freedom of expression, produces a quarterly magazine of the same name
• index.hu, a Hungarian-language news and community portal
• Indexed (cartoon), a Web cartoon by Jessica Hagy
• The Index, the student newspaper of Kalamazoo College
• The Index, an 1860s European propaganda journal created by Henry Hotze to support the Confederate States of America during the American Civil War or, a European informational journal supporting the rebellion against the United States of America during the War Between the States.
• The Index, an American freethought weekly paper published 1869-1886 by Benjamin Franklin Underwood
• Thumb index, a round cut-out in the pages of a publication
• Truman State University Index, the weekly student newspaper of Truman State University

Sciences

• Index (statistics), a concept in statistics, research design and social sciences
  • A scale (social sciences), a more advanced type of an index

Biological sciences

• Diversity index – a quantitative measure that increases when the number of types (distinct groups) into which a set of entities (a population) has been classified increases, and obtains its maximum value for a given number of types when all types are represented proportional to their number within the set of entities

Computer sciences

• Lookup table, a data structure, usually an array or associative array, often used to replace a runtime computation with a simpler array indexing operation
• Array index, an integer pointer (into an array data structure) that identifies an element of the array
• A key in an associative array
• Database index, a data structure that improves the speed of data retrieval operations on a database table
• Index mapping, mapping of raw data, used directly as in array index, for an array
• Index register, a processor register used for modifying operand addresses during the run of a program
• The dataset maintained by search engine indexing
• Indexed color
• Indexed Sequential Access Method (ISAM), a method for indexing data for fast retrieval
• Subject indexing, describing the content of a document by keywords
• Web indexing (Internet indexing)
• Site map, a list of pages of a web site accessible to crawlers or users
• Webserver directory index, a default or index web page in a directory on a web server, such as index.html
• BitTorrent index, a list of .torrent files available for searches

Economics

• Index (economics), a single number calculated from an array of prices and quantities
  • Price index, a typical price for some good or service

Geography

• Index, New York, a hamlet in the County and Town of Otsego, New York, United States
• Index, Washington, a town in Snohomish County, Washington, United States
• Index, West Virginia

Library and information science

• Back-of-the-book index
• Bibliographic index, a regularly updated print periodical publication that lists articles, books, and/or other information items,
• Index (publishing), a detailed list, usually arranged alphabetically, of the specific information in a publication
• Subject indexing, describing the content of a document by keywords

Linguistics

• Indexicality, the variation of meaning of an utterance according to certain features of the context in which it is uttered

Mathematics

• A number or other symbol that indicates the location of a variable in an indexed family or set
• A numerical value attached to a mathematical object, such as those listed here under Algebra and Analysis
• The index of summation i is used to calculate a sum

Algebra

• The degree of an nth root
• The index of a subgroup is the number of a subgroup's left cosets (which is equal to the number of its right cosets).
• The index of a linear map, is the dimension of the map's kernel minus the dimension of its cokernel.
• The index of a real quadratic form Q is defined (but not always consistently) as p − q, where Q can be written as a difference of p squared linear terms and q squared linear terms.
• The index of a matrix is the least integer k ≥ 0 such that rank(A^k+1) = rank(A^k).

Analysis

• The winding number of an oriented closed curve on a surface relative to a point on that surface; loosely speaking, the number of times the curve goes around the point counter-clockwise
• The index of a vector field v at an isolated zero is the degree of the map $x^{a}\mapsto {\frac {v^{a}(x)}{\sqrt {\sum _{b}(v^{b}(x))^{2}}}}$, taking points near the zero into the unit sphere111.

Technologies

Mechanics

• Indexing (motion), a kind of motion in many areas of mechanical engineering and machining

Optics

• Refractive index, a measure for optical properties of transparent materials.

Other usages

• Index, Arkansas, a community in the United States
• Index:, a Danish nonprofit organization which promotes Design for Life
• The Index, an item on a halo megastructure in the Halo series of video games
• The Index (Dubai), a skyscraper in Dubai
• INDEX was the pre-launch name for the Reimei satellite

See also

• All pages with titles beginning with index
• All pages with titles containing index