When an organization asks us to create a taxonomy or thesaurus, it’s usually because they want to be able to manage a collection.Taxonomies and thesauri are both types of controlled vocabularies. In controlled vocabularies intended for indexing, each concept covered by the vocabulary is represented by one and only one term that is valid for indexing. (True, a thesaurus contains synonyms, but in most computer-based thesauri, these take the form of “non-preferred” synonyms that point to the preferred terminology for the concept.) If the taxonomy or thesaurus is managed consistently, so they will get the same answers/results every time. They don’t want to get a different answer every time they do a search.