What Is A Reference

A reference, or a references point, is the intensional use of one thing, a point of reference or reference state, to indicate something else. When reference is intended, what the reference points to is called the referent.

General Examples
Some general examples are:

the name Jane Doe used to identify a particular woman;
a traffic sign warning of an upcoming turn-off;
a wedding ring indicating a certain kind of relationship; and
samples of various musical works being incorporated into a new one.
 

References are indicated by sounds (like onomatopoeia), pictures (like roadsigns), text (like bibliographies), indexes (by number) and objects (a wedding ring); but endless concrete and abstract methods can be used intentionally. This includes methods that intentionally hide the reference from some observers, as in cryptography.

The following sections give specific usages of reference in different subjects.