A reference is a relationship between objects in which one object designates, or acts as a means by which to connect to or link to, another object. The first object in this relation is said to ''refer to'' the second object. It is called a ''

name A name is a term used for identification by an external observer. They can identify a class or category of things, or a single thing, either uniquely, or within a given context. The entity identified by a name is called its referent. A person ...

'' for the second object. The next object, the one to which the first object refers, is called the ''

referent A referent ( ) is a person or thing to which a name – a linguistic expression or other symbol – refers. For example, in the sentence ''Mary saw me'', the referent of the word ''Mary'' is the particular person called Mary who is being spoken o ...

'' of the first object. A name is usually a

phrase In grammar, a phrasecalled expression in some contextsis a group of words or singular word acting as a grammatical unit. For instance, the English language, English expression "the very happy squirrel" is a noun phrase which contains the adject ...

or expression, or some other symbolic representation. Its referent may be anything – a material object, a person, an event, an activity, or an abstract concept. References can take on many forms, including: a thought, a sensory perception that is

audible Audible may refer to: * Audible (service), an online audiobook store * Audible (American football), a tactic used by quarterbacks * ''Audible'' (film), a short documentary film featuring a deaf high school football player * Audible finish or ru ...

(

onomatopoeia Onomatopoeia (or rarely echoism) is a type of word, or the process of creating a word, that phonetics, phonetically imitates, resembles, or suggests the sound that it describes. Common onomatopoeias in English include animal noises such as Oin ...

visual The visual system is the physiological basis of visual perception (the ability to detect and process light). The system detects, transduces and interprets information concerning light within the visible range to construct an image and buil ...

(text), olfactory, or tactile, emotional state, relationship with other,

spacetime In physics, spacetime, also called the space-time continuum, is a mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum. Spacetime diagrams are useful in visualiz ...

coordinates, symbolic or alpha-numeric, a physical object, or an energy projection. In some cases, methods are used that intentionally hide the reference from some observers, as in

cryptography Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), ...

. References feature in many spheres of human activity and knowledge, and the term adopts shades of meaning particular to the contexts in which it is used. Some of them are described in the sections below.

Etymology and meanings

The word ''reference'' is derived from

Middle English Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman Conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English pe ...

', from

Middle French Middle French () is a historical division of the French language that covers the period from the mid-14th to the early 17th centuries. It is a period of transition during which: * the French language became clearly distinguished from the other co ...

, from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

, "to carry back", formed from the

prefix A prefix is an affix which is placed before the stem of a word. Particularly in the study of languages, a prefix is also called a preformative, because it alters the form of the word to which it is affixed. Prefixes, like other affixes, can b ...

''re''- and ''ferre'', "to bear". A number of words derive from the same root, including ''refer'', ''

referee A referee is an official, in a variety of sports and competition, responsible for enforcing the rules of the sport, including sportsmanship decisions such as ejection. The official tasked with this job may be known by a variety of other title ...

'', ''referential'', ''

'', ''

referendum A referendum, plebiscite, or ballot measure is a Direct democracy, direct vote by the Constituency, electorate (rather than their Representative democracy, representatives) on a proposal, law, or political issue. A referendum may be either bin ...

''. The verb ''refer (to)'' and its derivatives may carry the sense of "connect to" or "link to", as in the meanings of ''reference'' described in this article. Another sense is "consult"; this is reflected in such expressions as

reference work A reference work is a document, such as a Academic publishing#Scholarly paper, paper, book or periodical literature, periodical (or their electronic publishing, electronic equivalents), to which one can refer for information. The information ...

reference desk The reference desk or information desk of a library is a public service counter where professional librarians provide library users with direction to library materials, advice on library collections and services, and expertise on multiple kinds ...

job reference A letter of recommendation or recommendation letter, also known as a letter of reference, reference letter, or simply reference, is a document in which the writer assesses the qualities, characteristics, and capabilities of the person being recomme ...

, etc.

Semantics

semantics Semantics is the study of linguistic Meaning (philosophy), meaning. It examines what meaning is, how words get their meaning, and how the meaning of a complex expression depends on its parts. Part of this process involves the distinction betwee ...

, reference is generally construed as the relationships between

noun In grammar, a noun is a word that represents a concrete or abstract thing, like living creatures, places, actions, qualities, states of existence, and ideas. A noun may serve as an Object (grammar), object or Subject (grammar), subject within a p ...

s or

pronoun In linguistics and grammar, a pronoun (Interlinear gloss, glossed ) is a word or a group of words that one may substitute for a noun or noun phrase. Pronouns have traditionally been regarded as one of the part of speech, parts of speech, but so ...

s and objects that are named by them. Hence, the

word A word is a basic element of language that carries semantics, meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no consensus among linguist ...

"John" refers to the person John. The word "it" refers to some previously specified object. The object referred to is called the ''

'' of the word. Sometimes the word-object relation is called "

denotation In linguistics and philosophy, the denotation of a word or expression is its strictly literal meaning. For instance, the English word "warm" denotes the property of having high temperature. Denotation is contrasted with other aspects of meaning in ...

"; the word denotes the object. The converse relation, the relation from object to word, is called "

exemplification Exemplification, in the philosophy of language, is a mode of symbolization characterized by the relation between a sample and what it refers to. Description Unlike ostension, which is the act of showing or pointing to a sample, exemplification ...

"; the object exemplifies what the word denotes. In syntactic analysis, if a word refers to a previous word, the previous word is called the " antecedent".

Meaning

Gottlob Frege Friedrich Ludwig Gottlob Frege (; ; 8 November 1848 – 26 July 1925) was a German philosopher, logician, and mathematician. He was a mathematics professor at the University of Jena, and is understood by many to be the father of analytic philos ...

argued that reference cannot be treated as identical with meaning: " Hesperus" (an ancient Greek name for the evening star) and "

Phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

" (an ancient Greek name for the morning star) both refer to

Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...

, but the astronomical fact that '"Hesperus" is "Phosphorus"' can still be informative, even if the "meanings" of "Hesperus" and "Phosphorus" are already known. This problem led Frege to distinguish between the

sense and reference In the philosophy of language, the distinction between sense and reference was an idea of the German philosopher and mathematician Gottlob Frege in 1892 (in his paper "On Sense and Reference"; German: "Über Sinn und Bedeutung"), reflecting the ...

of a word.

Linguistic sign

The very concept of the linguistic sign is the combination of content and expression, the former of which may refer entities in the world or refer more abstract concepts, e.g. thought. Certain parts of speech exist only to express reference, namely anaphora such as

s. The subset of reflexives expresses co-reference of two participants in a sentence. These could be the agent (actor) and patient (acted on), as in "The man washed himself", the theme and recipient, as in "I showed Mary to herself", or various other possible combinations.

Computer science

computer science Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, ...

reference A reference is a relationship between objects in which one object designates, or acts as a means by which to connect to or link to, another object. The first object in this relation is said to ''refer to'' the second object. It is called a ''nam ...

s are

data type In computer science and computer programming, a data type (or simply type) is a collection or grouping of data values, usually specified by a set of possible values, a set of allowed operations on these values, and/or a representation of these ...

s that refer to an object elsewhere in memory and are used to construct a wide variety of

data structure In computer science, a data structure is a data organization and storage format that is usually chosen for Efficiency, efficient Data access, access to data. More precisely, a data structure is a collection of data values, the relationships amo ...

s, such as

linked list In computer science, a linked list is a linear collection of data elements whose order is not given by their physical placement in memory. Instead, each element points to the next. It is a data structure consisting of a collection of nodes whi ...

s. Generally, a reference is a value that enables a program to directly access the particular data item. Most

programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...

s support some form of reference. For the specific type of reference used in the C++ language, see reference (C++). The notion of reference is also important in relational

database theory Database theory encapsulates a broad range of topics related to the study and research of the theoretical realm of databases and database management systems. Theoretical aspects of data management include, among other areas, the foundations of q ...

; see referential integrity.

Library and information sciences

References to many types of printed matter may come in an electronic or machine-readable form. For books, there exists the

ISBN The International Standard Book Number (ISBN) is a numeric commercial book identifier that is intended to be unique. Publishers purchase or receive ISBNs from an affiliate of the International ISBN Agency. A different ISBN is assigned to e ...

and for journal articles, the Digital object identifier (DOI) is gaining relevance. Information on the

Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...

may be referred to by a Uniform Resource Identifier (URI).

Psychology

In terms of mental processing, a

self-reference Self-reference is a concept that involves referring to oneself or one's own attributes, characteristics, or actions. It can occur in language, logic, mathematics, philosophy, and other fields. In natural or formal languages, self-reference ...

is used in psychology to establish identification with a mental state during self-analysis. This seeks to allow the individual to develop own frames of reference in a greater state of immediate awareness. However, it can also lead to

circular reasoning Circular reasoning (, "circle in proving"; also known as circular logic) is a fallacy, logical fallacy in which the reasoner begins with what they are trying to end with. Circular reasoning is not a formal logical fallacy, but a pragmatic defect ...

, preventing evolution of thought. According to Perceptual Control Theory (PCT), a reference condition is the state toward which a control system's output tends to alter a controlled quantity. The main proposition is that "All behavior is oriented all of the time around the control of certain quantities with respect to specific reference conditions."

Scholarship

In academics and scholarship, a reference or bibliographical reference is a piece of information provided in a

footnote In publishing, a note is a brief text in which the author comments on the subject and themes of the book and names supporting citations. In the editorial production of books and documents, typographically, a note is usually several lines of tex ...

bibliography Bibliography (from and ), as a discipline, is traditionally the academic study of books as physical, cultural objects; in this sense, it is also known as bibliology (from ). English author and bibliographer John Carter describes ''bibliograph ...

of a

written work Writing is the act of creating a persistent representation of language. A writing system includes a particular set of symbols called a ''script'', as well as the rules by which they encode a particular spoken language. Every written language ...

such as a book, article, essay, report, oration or any other

text Text may refer to: Written word * Text (literary theory) In literary theory, a text is any object that can be "read", whether this object is a work of literature, a street sign, an arrangement of buildings on a city block, or styles of clothi ...

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

, specifying the written work of another person used in the creation of that text. A bibliographical reference mostly includes the full name of the

author In legal discourse, an author is the creator of an original work that has been published, whether that work exists in written, graphic, visual, or recorded form. The act of creating such a work is referred to as authorship. Therefore, a sculpt ...

, the title of their work and the year of publication. The primary purpose of references is to allow readers to examine the sources of a text, either for validity or to learn more about the subject. Such items are often listed at the end of a work in a section marked ''References'' or ''Bibliography''. References are particularly important as for the use of

citation A citation is a reference to a source. More precisely, a citation is an abbreviated alphanumeric expression embedded in the body of an intellectual work that denotes an entry in the bibliographic references section of the work for the purpose o ...

s, since

copying Copying is the duplication of information or an wiktionary:artifact, artifact based on an instance of that information or artifact, and not using the process that originally generated it. With Analog device, analog forms of information, copying is ...

of material by another author without proper reference and / or without required permissions is considered

plagiarism Plagiarism is the representation of another person's language, thoughts, ideas, or expressions as one's own original work.From the 1995 ''Random House Dictionary of the English Language, Random House Compact Unabridged Dictionary'': use or close ...

, and may be tantamount to

copyright infringement Copyright infringement (at times referred to as piracy) is the use of Copyright#Scope, works protected by copyright without permission for a usage where such permission is required, thereby infringing certain exclusive rights granted to the c ...

, which can be subject to

legal proceeding Legal proceeding is an activity that seeks to invoke the power of a tribunal in order to enforce a law. Although the term may be defined more broadly or more narrowly as circumstances require, it has been noted that " e term ''legal proceedings ...

s. A ''reference'' section contains only those works indeed cited in the main text of a work. In contrast, a ''bibliographical'' section often contains works not cited by the author, but used as background reading or listed as potentially useful to the reader. Keeping a

diary A diary is a written or audiovisual memorable record, with discrete entries arranged by date reporting on what has happened over the course of a day or other period. Diaries have traditionally been handwritten but are now also often digita ...

allows an individual to use references for personal organization, whether or not anyone else understands the systems of reference used. However, scholars have studied methods of reference because of their key role in communication and co-operation between ''different'' people, and also because of misunderstandings that can arise. Modern academic study of bibliographical references has been developing since the 19th century.

Law

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...

law, a reference is a document that can be used to show the state of knowledge at a given time and that therefore may make a claimed

invention An invention is a unique or novelty (patent), novel machine, device, Method_(patent), method, composition, idea, or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It m ...

obvious or anticipated. Examples of references are patents of any country, magazine articles, Ph.D. theses that are indexed and thus accessible to those interested in finding information about the subject matter, and to some extent Internet material that is similarly accessible.

Arts

art Art is a diverse range of cultural activity centered around ''works'' utilizing creative or imaginative talents, which are expected to evoke a worthwhile experience, generally through an expression of emotional power, conceptual ideas, tec ...

, a reference is an item from which a work is based. This may include: * an existing artwork * a reproduction (i.e., a photo) * a directly observed object (e.g., a person) * the artist's memory Another example of reference is samples of various musical works being incorporated into a new one.

References

External links

Reference.com
– a multi-source encyclopedia search service, and language reference products provider *
References.net
– a directory of multidisciplinary reference resources on the web
Refmuseum.com
– The online museum of references {{logic Semantics Philosophical logic Concepts in logic Syntactic relationships Meaning (philosophy of language) Formal semantics (natural language)