Controlled vocabulary

The phrase controlled vocabulary is often used to denote that the concepts are managed in some way and that it is only possible to choose from amongst these concepts. A controlled vocabulary is a list of terms that are related to each other in some way: they should all be about the same thing. They are often also referred to as authority files as they represent an authoritative set of descriptions for a list of terms. The control aspect refers both to the fact that the terms available are specific and limited (for example, a folksonomy is not a controlled vocabulary, because it is not constrained to a particular set of terms) and also to the fact that such vocabularies have a set of house rules and management processes governing them.