A taxonomy is a classification system on one or more topic areas that has the following features:

• hierarchy (i.e. a way of navigating to broader and narrower terms
• enumeration (a term is composed of these components)
• equivalence (this term is equivalent to that term)
• membership rules (how many terms can an object have?)
• associative references (this term is similar to these other terms)

For an interesting discussion on taxonomies, vocabularies, and classification systems, see this description.Taxonomies on this site are used to classify postings according to one or more different vocabularies. Generally, these classifications are optional, but if they are used, they allow readers to browse to other content which also has that classification. You can request the addition of new vocabularies or terms, or changes to the architecture currently in place for existing vocabularies, by posting a comment to this node and describing the rationale for your request.