information science An information resource that contains references to other resources, categorised by subject, usually in a
hierarchy.
Yahoo is the most popular
Internet subject index. Like most other subject indices (https://yahoo.com/Computers_and_Internet/Internet/World_Wide_Web/Searching_the_Web/Web_Directories/), Yahoo is arranged
ontologically.
Subject indices are not to be confused with
search engines, which are based not on subject, but instead on
relevance, although (1) this difference is often (possibly rightly) hidden from the unsophisticated user, and (2) future integration of
knowledge representation into relevance ranking
algorithms will make this a hazy distinction.
(1997-04-09)