
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 documents. Examples are an index in the
back matter of a
book
A book is a medium for recording information in the form of writing or images, typically composed of many pages (made of papyrus, parchment, vellum, or paper) bound together and protected by a cover. The technical term for this phys ...
and an index that serves as a
library catalog
A library catalog (or library catalogue in British English) is a register of all bibliographic items found in a library or group of libraries, such as a network of libraries at several locations. A catalog for a group of libraries is also ...
. An index differs from a word index, or
''concordance'', in focusing on the subject of the text rather than the exact words in a text, and it differs from a
table of contents
A table of contents, usually headed simply Contents and abbreviated informally as TOC, is a list, usually found on a page before the start of a written work, of its chapter or section titles or brief descriptions with their commencing page number ...
because the index is ordered by subject, regardless of whether it is early or late in the book, while the listed items in a table of contents is placed in the same order as the book.
In a traditional ''back-of-the-book index'', the headings will include names of people, places, events, and concepts selected as being relevant and of interest to a possible reader of the book. The indexer performing the selection may be the author, the editor, or a professional indexer working as a third party. The pointers are typically page numbers, paragraph numbers or section numbers.
In a
library catalog
A library catalog (or library catalogue in British English) is a register of all bibliographic items found in a library or group of libraries, such as a network of libraries at several locations. A catalog for a group of libraries is also ...
the words are authors, titles, subject headings, etc., and the pointers are
call numbers. Internet
search engines (such as
Google
Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...
) and full-text searching help provide access to information but are not as selective as an index, as they provide non-relevant links, and may miss relevant information if it is not phrased in exactly the way they expect.
Perhaps the most advanced investigation of problems related to book indexes is made in the development of
topic maps, which started as a way of representing the knowledge structures inherent in traditional back-of-the-book indexes. The
concept
Concepts are defined as abstract ideas. They are understood to be the fundamental building blocks of the concept behind principles, thoughts and beliefs.
They play an important role in all aspects of cognition. As such, concepts are studied by s ...
embodied by book indexes lent its name to
database indexes, which similarly provide an abridged way to look up information in a larger collection, albeit one for computer use rather than human use.
Earliest examples in English
In the English language, indexes have been referred to as early as 1593, as can be seen from lines in
Christopher Marlowe's ''
Hero and Leander
Hero and Leander is the Greek myth relating the story of Hero ( grc, Ἡρώ, ''Hērṓ''; ), a priestess of Aphrodite ( Venus in Roman mythology) who dwelt in a tower in Sestos on the European side of the Hellespont, and Leander ( grc, Λέ ...
'' of that year:
''Therefore, even as an index to a book''
''So to his mind was young Leander's look.''
A similar reference to indexes is in
Shakespeare
William Shakespeare ( 26 April 1564 – 23 April 1616) was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's natio ...
's lines from ''
Troilus and Cressida
''Troilus and Cressida'' ( or ) is a play by William Shakespeare, probably written in 1602.
At Troy during the Trojan War, Troilus and Cressida begin a love affair. Cressida is forced to leave Troy to join her father in the Greek camp. M ...
'' (I.3.344), written nine years later:
''And in such indexes, although small pricks''
''To their subsequent volumes, there is seen''
''The baby figure of the giant mass''
''Of things to come at large.''

But according to G. Norman Knight, "at that period, as often as not, by an 'index to a book' was meant what we should now call a table of contents."
[Knight, G. Norman (1979) ''Indexing, the Art of: A Guide to the Indexing of Books and Periodicals'' (HarperCollins), pp. 17–18] Until about the end of the nineteenth century, books, fiction as well as non-fiction, sometimes had very detailed chapter titles, which could be several sentences long.
Among the first indexes – in the modern sense – to a book in the English language was Leonard Mascall's "A booke of the arte and maner how to plant and graffe all sortes of trees" printed in 1575. Another was one in
Plutarch
Plutarch (; grc-gre, Πλούταρχος, ''Ploútarchos''; ; – after AD 119) was a Greek Middle Platonist philosopher, historian, biographer, essayist, and priest at the Temple of Apollo in Delphi. He is known primarily for his ...
's ''
Parallel Lives
Plutarch's ''Lives of the Noble Greeks and Romans'', commonly called ''Parallel Lives'' or ''Plutarch's Lives'', is a series of 48 biographies of famous men, arranged in pairs to illuminate their common moral virtues or failings, probably writt ...
'', in Sir
Thomas North's 1595 translation.
A section entitled "An Alphabetical Table of the most material contents of the whole book" may be found in
Henry Scobell's ''Acts and Ordinances of Parliament'' of 1658. This section comes after "An index of the general titles comprised in the ensuing Table".
Both of these indexes predate the index to
Alexander Cruden
Alexander Cruden (31 May 16991 November 1770) was the Scottish author of an early concordance to the Bible, a proofreader and publisher, and self-styled Corrector of the nation's morals.
Early life and career
Alexander Cruden was born in Aber ...
's ''Concordance'' (1737), which is erroneously held to be the earliest index found in an English book.
Etymology and plural
The word is derived from
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
, in which ''index'' means "one who points out", an "indication", or a "
forefinger".
In Latin, the plural form of the word is ''indices''. In English, the plural "indices" is commonly used in
mathematical
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
and
computing contexts, and sometimes in bibliographical contexts – for example, in the 17-volume ''
Women in World History: A Biographical Encyclopedia'' (1999–2002). However, this form is now seen as an archaism by many writers and commentators, who prefer the anglicised plural "indexes". "Indexes" is widely used in the publishing industry; in the International Standard
ISO 999, ''Information and documentation – Guidelines for the content, organization and presentation of indexes''; and is preferred by the ''
Oxford Style Manual''. ''
The Chicago Manual of Style
''The Chicago Manual of Style'' (abbreviated in writing as ''CMOS'' or ''CMS'', or sometimes as ''Chicago'') is a style guide for American English published since 1906 by the University of Chicago Press. Its 17 editions have prescribed writ ...
'' allows both forms.
G. Norman Knight quotes
Shakespeare
William Shakespeare ( 26 April 1564 – 23 April 1616) was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's natio ...
's lines from ''
Troilus and Cressida
''Troilus and Cressida'' ( or ) is a play by William Shakespeare, probably written in 1602.
At Troy during the Trojan War, Troilus and Cressida begin a love affair. Cressida is forced to leave Troy to join her father in the Greek camp. M ...
'' (I.3.344) – "And in such indexes ..." – and comments:
"But the real importance of this passage is that it establishes for all time the correct literary plural; we can leave the Latin form "indices" to the mathematicians (and similarly "appendices" to the anatomists)."
Indexing process
Conventional indexing
The indexer reads through the text, identifying indexable concepts (those for which the text provides useful information and which will be of relevance for the text's readership). The indexer creates index headings to represent those concepts, which are phrased such that they can be found when in alphabetical order (so, for example, one would write 'indexing process' rather than 'how to create an index'). These headings and their associated locators (indicators to position in the text) are entered into specialist
indexing software which handles the formatting of the index and facilitates the editing phase. The index is then edited to impose consistency throughout the index.
Indexers must analyze the text to enable presentation of concepts and ideas in the index that may not be named within the text. The index is intended to help the reader, researcher, or information professional, rather than the author, find information, so the professional indexer must act as a liaison between the text and its ultimate user.
In the United States, according to tradition, the index for a non-fiction book is the responsibility of the author, but most authors don't actually do it. Most indexing is done by freelancers hired by authors, publishers or an independent business which manages the production of a book, publishers or
book packagers
A book is a medium for recording information in the form of writing or images, typically composed of many pages (made of papyrus, parchment, vellum, or paper) bound together and protected by a cover. The technical term for this physical arra ...
. Some publishers and database companies employ indexers.
Before indexing software existed, indexes were created using slips of paper or, later,
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 ...
s. After hundreds of such slips or cards were filled out (as the indexer worked through the pages of the book proofs), they could then be shuffled by hand into alphabetical order, at which point they served as
manuscript
A manuscript (abbreviated MS for singular and MSS for plural) was, traditionally, any document written by hand – or, once practical typewriters became available, typewritten – as opposed to mechanically printed or reproduced ...
to be typeset into the printed index.
Indexing software
Software is available to aid the indexer in building a book index.
There are several dedicated indexing software programs available to assist with the special sorting and copying needs involved in index preparation.
Embedded indexing
Embedded indexing involves including the index headings in the midst of the text itself, but surrounded by codes so that they are not normally displayed. A usable index is then generated automatically from the embedded text using the position of the embedded headings to determine the locators. Thus, when the pagination is changed the index can be regenerated with the new locators.
LaTeX
Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latexes are found in nature, but synthetic latexes are common as well.
In nature, latex is found as a milky fluid found in 10% of all flowering plants (angiosper ...
documents support embedded indexes primarily through the
MakeIndex package. Several widely used
XML
Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. ...
DTDs, including
DocBook and
TEI, have elements that allow index creation directly in the XML files. Most
word processing software, such as
StarWriter/
OpenOffice.org Writer,
Microsoft Word
Microsoft Word is a word processing software developed by Microsoft. It was first released on October 25, 1983, under the name ''Multi-Tool Word'' for Xenix systems. Subsequent versions were later written for several other platforms includi ...
, and
WordPerfect, as well as some desktop publishing software (for example,
FrameMaker and
InDesign), as well as other tools (for example,
MadCap Software's Flare), have some facility for embedded indexing as well. TExtract and IndexExploit support embedded indexing of Microsoft Word documents.
[
An embedded index requires more time to create than a conventional static index; however, an embedded index can save time in the long run when the material is updated or repaginated. This is because, with a static index, if even a few pages change, the entire index must be revised or recreated while, with an embedded index, only the pages that changed need updating or indexing.
]
Purpose
Indexes are also designed to help the reader find information quickly and easily. A complete and truly useful index is not simply a list of the words and phrases used in a publication (which is properly called a concordance), but an organized map of its contents, including cross-reference
The term cross-reference (abbreviation: xref) can refer to either:
* An instance within a document which refers to related information elsewhere in the same document. In both printed and online dictionaries cross-references are important because ...
s, grouping of like concepts, and other useful intellectual analysis.
Sample back-of-the-book index excerpt:
:sage, 41–42. ''See also'' Herbs ← directing the reader to related terms
:Scarlet Sages. ''See'' ''Salvia coccinea'' ← redirecting the reader to term used in the text
:shade plants ← grouping term (may not appear in the text; may be generated by indexer)
::hosta, 93 ← subentries
::myrtle, 46
::Solomon's
:sunflower, 47 ← regular entry
In books, indexes are usually placed near the end (this is commonly known as "BoB" or back-of-book indexing). They complement the table of contents
A table of contents, usually headed simply Contents and abbreviated informally as TOC, is a list, usually found on a page before the start of a written work, of its chapter or section titles or brief descriptions with their commencing page number ...
by enabling access to information by specific subject, whereas contents listings enable access through broad divisions of the text arranged in the order they occur. It has been remarked that, while " first glance the driest part of the book, on closer inspection the index may provide both interest and amusement from time to time."
Index quality
Some principles of good indexing include:
* Ensuring each topic/section includes a variety of relevant index entries; use two or three entries per topic
* Understanding the audience and understand what kind of index entries they're likely to look for
* Use the same form throughout (singular vs. plural, capitalisation, etc.), using standard indexing conventions
Indexing pitfalls:
* Significant topics with no index entries at all
* Indexing 'mere mentions': "But John Major was no Winston Churchill..." indexed under 'Churchill, Winston'
* Circular cross-references: 'Felidae. ''See'' Cats'; 'Cats. ''See'' Felidae'
* References to discussions of a single topic scattered among several main headings: 'Cats, 50–62'; 'Felidae, 175–183'
* Inconsistently indexing similar topics
* Confusing similar names: Henry V of England, Henri V of France
* Incorrect alphabetization: 'α-Linolenic acid' under 'A' instead of 'L'
* Inappropriate inversions: 'processors, word' for 'word processors'
* Inappropriate subheadings: 'processors: food, 213–6; word, 33–7'
* Computer indexing from section headings: e.g. 'Getting to know your printer' under 'G'
Indexer roles
Some indexers specialize in specific formats, such as scholarly books, microforms, web indexing (the application of a back-of-book-style index to a website
A website (also written as a web site) is a collection of web pages and related content that is identified by a common domain name and published on at least one web server. Examples of notable websites are Google, Facebook, Amazon, and Wikip ...
or intranet), search engine indexing, database indexing (the application of a pre-defined controlled vocabulary
Control may refer to:
Basic meanings Economics and business
* Control (management), an element of management
* Control, an element of management accounting
* Comptroller (or controller), a senior financial officer in an organization
* Controll ...
such as MeSH
A mesh is a barrier made of connected strands of metal, fiber, or other flexible or ductile materials. A mesh is similar to a web or a net in that it has many attached or woven strands.
Types
* A plastic mesh may be extruded, oriented, e ...
to articles for inclusion in a database), and periodical indexing (indexing of newspapers, journals, magazines).
Some indexers with expertise in controlled vocabularies also work as taxonomists and ontologists.
Some indexers specialize in particular subject areas, such as anthropology, business, computers, economics, education, government documents, history, law, mathematics, medicine, psychology, and technology. An indexer can be found for any subject.
References in popular culture
In "The Library of Babel
"The Library of Babel" ( es, La biblioteca de Babel) is a short story by Argentine author and librarian Jorge Luis Borges (1899–1986), conceiving of a universe in the form of a vast library containing all possible 410-page books of a certain f ...
", a short story by Jorge Luis Borges
Jorge Francisco Isidoro Luis Borges Acevedo (; ; 24 August 1899 – 14 June 1986) was an Argentine short-story writer, essayist, poet and translator, as well as a key figure in Spanish-language and international literature. His best-known b ...
, there is an index of indexes that catalogues all of the books in the library, which contains all possible books.
Kurt Vonnegut
Kurt Vonnegut Jr. (November 11, 1922 – April 11, 2007) was an American writer known for his satirical and darkly humorous novels. In a career spanning over 50 years, he published fourteen novels, three short-story collections, five plays, and ...
's novel '' Cat's Cradle'' includes a character who is a professional indexer and believes that "indexing sa thing that only the most amateurish author ndertakesto do for his own book." She claims to be able to read an author's character through the index he created for his own history text, and warns the narrator, an author, "Never index your own book."
Vladimir Nabokov
Vladimir Vladimirovich Nabokov (russian: link=no, Владимир Владимирович Набоков ; 2 July 1977), also known by the pen name Vladimir Sirin (), was a Russian-American novelist, poet, translator, and entomologist. Bor ...
's novel ''Pale Fire
''Pale Fire'' is a 1962 novel by Vladimir Nabokov. The novel is presented as a 999-line poem titled "Pale Fire", written by the fictional poet John Shade, with a foreword, lengthy commentary and index written by Shade's neighbor and academic col ...
'' includes a parody of an index, reflecting the insanity of the narrator.
Mark Danielewski's novel '' House of Leaves'' contains an exhaustive 41 page index of words in the novel, including even large listings for inconsequential words such as ''the'', ''and'', and ''in''.
J. G. Ballard
James Graham Ballard (15 November 193019 April 2009) was an English novelist, short story writer, satirist, and essayist known for provocative works of fiction which explored the relations between human psychology, technology, sex, and mass me ...
's "The Index" is a short story told through the form of an index to an "unpublished and perhaps suppressed" autobiography.
Standards
* ISO 999:1996 Guidelines for the Content, Organization, and Presentation of Indexes (this is also the national standard in the UK, Australia, and New Zealand)
Societies
Th
American Society for Indexing, Inc.
(ASI) is a national association founded in 1968 to promote excellence in indexing and increase awareness of the value of well-designed indexes. ASI serves indexers, librarians, abstractors, editors, publishers, database producers, data searchers, product developers, technical writers, academic professionals, researchers and readers, and others concerned with indexing. It is the only professional organization in the United States devoted solely to the advancement of indexing, abstracting and related methods of information retrieval.
Other similar societies include:
* Association of Southern African Indexers and Bibliographers (ASAIB)
* Australian and New Zealand Society of Indexers
* British Record Society
* China Society of Indexers
* German Network of Indexers/Deutsches Netzwerk der Indexer (DNI)
* Indexing Society of Canada/Société canadienne d'indexation (ISC/SCI)
* Nederlands Indexers Netwerk (NIN)
* Society of Indexers
See also
* Concordance (publishing)
* Indexing and abstracting service
* ''Index, A History of the
''Index, A History of the: A Bookish Adventure from Medieval Manuscripts to the Digital Age'' is a 2022 book by Dennis Duncan that examines the history of indexes. The book has five "positive" reviews, ten "rave" reviews, and one "mixed" review ...
''
* Subject (documents)
* Subject indexing
* Table of contents
A table of contents, usually headed simply Contents and abbreviated informally as TOC, is a list, usually found on a page before the start of a written work, of its chapter or section titles or brief descriptions with their commencing page number ...
* Web indexing
References
Further reading
* Booth, Pat (2001) ''Indexing: The Manual of Good Practice'' (K. G. Saur),
* Borko, Harold & Bernier, Charles L. (1978) ''Indexing Concepts and Methods'',
* Browne, Glenda and Jermey, Jon (2007), ''The Indexing Companion'' (Cambridge University Press),
* Diodato, V. (1994). User preferences for features in back of book indexes. Journal of the American Society for Information Science. 45(7), 529–536.
* Diodato, V. & Gandt, G. (1991). Back of book indexes and the characteristics of author and nonauthor indexing: Report of an exploratory study. Journal of the American Society for Information Science. 42(5), 341–350.
* Enser, P. G. B. (1985). Automatic classification of book material represented by back-of-the-book index. Journal of Documentation. 41(3), 135–155.
* Fugmann, R. (2006). Das Buchregister Methodische Grundlagen und praktische Anwendung. Frankfurt am Main : DGI. (DGI Schrift; Informationswissenschaft – 10).
* Grosch, A. N. (1986). Index-aid: Computer assisted back-of-the-book indexing. Electronic Library. 4(5), 278–280.
* Hornyak, B. (2002). Indexing Specialties: Psychology. Medford, NJ : Information Today, Inc.
* Kendrick, P. & Zafran, E. L. (Eds.). (2001). Indexing Specialties: Law. Medford, NJ : Information Today, Inc.
* Mulvany, Nancy (2005) ''Indexing Books'', 2nd ed. (University of Chicago Press)
* School of Library, archival and information studies, The University of British Columbia. Indexing resources on the WWW. Back-of-the-Book indexing. Hentet fra: https://web.archive.org/web/20140805233922/http://www.slais.ubc.ca/resources/indexing/backof2.htm
* Schütze, H. (1998). The Hypertext Concordance: A Better Back-of-the-Book Index. I: Proceedings of Computerm ´98 (Montreal, Canada, 1998). D. Bourigault, C. Jacquemin, and M.-C. L´Homme, Eds., pp. 101–104.
* Smith, Sherry & Kells, Kari (2005) ''Inside Indexing: the Decision-Making Process'' (Northwest Indexing Press),
* Stauber, Do Mi (2004) ''Facing the Text: Content and Structure in Book Indexing'' (Cedar Row Press)
* Towery, M. (Ed.). (1998). Indexing Specialties: History. Medford, NJ : Information Today, Inc.
* Wellisch, Hans (1995) ''Indexing from A to Z'', 2nd ed. (H. W. Wilson)
* Wellisch, Hans, H. (1986). "The Oldest Printed Indexes." ''The Indexer'' vol 15 no 2 October., pp. 1–10.
* Witty, F. J. (1965). Early indexing techniques. ''Library Quarterly 35,'' 141–148.
* Witty, F. J. (1973). Beginnings of indexing and abstracting: some notes towards a history of indexing and abstracting in antiquity and the Middle Ages. ''The Indexer : Journal of the Society of Indexers.'', 8, 193–198.
* Wu, Z. etc. (2013). Can Back-of-the-Book Indexes be Automatically Created? In Proceedings of CIKM 2013. San Francisco, CA, USA.
* Wyman, L. P. (Ed.). (1999). Indexing Specialities: Medicine. Medford, NJ : Information Today, Inc.
External links
The Indexer (the international journal)
Usability studies for indexes
"The Definite Article: Acknowledging 'The' in Index Entries
", Glenda Browne, The Indexer, vol. 22, no. 3 April 2001, pp. 119–22.
The role of indexing in technical communication
{{Authority control
Book publishing
Book terminology
Book design
Information science
Publishing