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 for the second object. The next object, the one to which the first object refers, is called the referent 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, or tactile, emotional state, relationship with other,[1] spacetime 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.[citation needed]
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.
The word reference is derived from Middle English referren, from Middle French référer, from Latin referre, "to carry back", formed from the prefix re- and ferre, "to bear".[2] A number of words derive from the same root, including refer, referee, referential, referent, 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.
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 referent of the word.[3] Sometimes the word-object relation is called "denotation"; 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".