The classic approach of Frege posits
three elements to any reference: the name, the
sense, and the referent (Frege, 1892).
The sense is the mode of presentation, a type of public,
objective knowledge about the item.
In Frege's classical example, Hesperus
has a sense (``the morning star'') different from that of
Phosphorus (``the evening star''), yet both have the same
referent, the planet Venus.
Russsel and Co.'s descriptivist theory of names analyses
the sense of a name as identifying a set definite descriptive terms.