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 personal ...

'' for the second object. The second 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 of, ...

'' of the first object. A name is usually a phrase 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 ( onomatopoeia), visual (text),

olfactory The sense of smell, or olfaction, is the special sense through which smells (or odors) are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste. In humans, it ...

, or tactile, emotional state, relationship with other, spacetime coordinate,

symbolic Symbolic may refer to: * Symbol, something that represents an idea, a process, or a physical entity Mathematics, logic, and computing * Symbolic computation, a scientific area concerned with computing with mathematical formulas * Symbolic dynamic ...

alpha-numeric Alphanumericals or alphanumeric characters are a combination of alphabetical and numerical characters. More specifically, they are the collection of Latin letters and Arabic digits. An alphanumeric code is an identifier made of alphanumeric ch ...

, a physical object or an energy projection. In some cases, methods are used that intentionally hide the reference from some observers, as in 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 ', from Middle French ''référer'', from Latin ''referre'', "to carry back", formed from the

prefix A prefix is an affix which is placed before the Word stem, stem of a word. Adding it to the beginning of one word changes it into another word. For example, when the prefix ''un-'' is added to the word ''happy'', it creates the word ''unhappy'' ...

''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 titl ...

'', ''referential'', ''

'', '' referendum''. 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, reference desk, job reference, etc.

Semantics

In semantics, reference is generally construed as the relationships between nouns or pronouns and objects that are named by them. Hence, the word "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 an expression is its literal meaning. For instance, the English word "warm" denotes the property of being warm. Denotation is contrasted with other aspects of meaning including connotation. For inst ...

"; the word denotes the object. The converse relation, the relation from object to word, is called " 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 An antecedent is a preceding event, condition, cause, phrase, or word. The etymology is from the Latin noun ''antecedentem'' meaning "something preceding", which comes from the preposition ''ante'' ("before") and the verb ''cedere'' ("to go"). ...

Meaning

Gottlob Frege argued that reference cannot be treated as identical with

meaning Meaning most commonly refers to: * Meaning (linguistics), meaning which is communicated through the use of language * Meaning (philosophy), definition, elements, and types of meaning discussed in philosophy * Meaning (non-linguistic), a general te ...

: " Hesperus" (an ancient Greek name for the evening star) and " Phosphorus" (an ancient Greek name for the morning star) both refer to Venus, 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 of a word. Some cases seem to be too complicated to be classified within this framework; the acceptance of the notion of secondary reference may be necessary to fill the gap. See also Opaque context.

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 pronouns. 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

In computer science, references are

data type In computer science and computer programming, a data type (or simply type) is a set of possible values and a set of allowed operations on it. A data type tells the compiler or interpreter how the programmer intends to use the data. Most progra ...

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, management, and storage format that is usually chosen for efficient access to data. More precisely, a data structure is a collection of data values, the relationships among them, a ...

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 whic ...

s. Generally, a reference is a value that enables a program to directly access the particular data item. Most programming languages 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; 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 and for journal articles, the Digital object identifier (DOI) is gaining relevance. Information on the Internet may be referred to by a Uniform Resource Identifier (URI).

Psychology

In terms of mental processing, a

self-reference Self-reference occurs in natural or formal languages when a sentence, idea or formula refers to itself. The reference may be expressed either directly—through some intermediate sentence or formula—or by means of some encoding. In philoso ...

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, 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 or

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 ''bibliography ...

of a written work such as a book, article, essay, report, oration or any other text

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. * Ty ...

, 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, 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 Validity or Valid may refer to: Science/mathematics/statistics: * Validity (logic), a property of a logical argument * Scientific: ** Internal validity, the validity of causal inferences within scientific studies, usually based on experiments ...

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 of ...

s, since

copying Copying is the duplication of information or an artifact based on an instance of that information or artifact, and not using the process that originally generated it. With analog forms of information, copying is only possible to a limited degree o ...

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

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

, and may be tantamount to copyright infringement, which can be subject to legal proceedings. 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 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

In patent 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 novel device, method, composition, idea or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It may also be an entirely new concept. If an i ...

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

In art, 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)