In the DAM world we often hear a group of terms being used to describe aspects of the DAM process. So what is the difference between SUBJECT INDEXING, ONTOLOGY, KEYWORDS and THESAURUS?

Link to definitions for: Metadata, Controlled Vocabulary and Taxonomy

SUBJECT INDEXING: the act of describing or classifying an asset by an index of terms or other symbols to indicate what the asset is about, to summarize its content or to increase its find-ability. It indentifies and describes the SUBJECT of the asset.

ONTOLOGY: Shows a self-described network of relationships, properties and functions. It is used to track how items or words relate to one another particularly as they relate to intelligent navigation.

KEYWORDS: are assigned to an asset to describe what the asset is about. Ideally keywords would come from an authorized subject indexing list or controlled vocabulary, but usually are assigned by other methods.

THESAURUS: a hierarchical set of terms about a particular field or set of concepts or collection, which define relationships among the terms through authority files and a standardized set of relationship indicators, like broader terms, narrower terms, related terms, preferred and non-preferred terms.

Slawsky, Donna; Building a keyword library for description of visual assets: Thesaurus basics; Journal of Digital Asset Management (2007) 3, 130–138
accessed: January 15, 2013