Controlled vocabulary is a standardized, pre-defined set of terms used by a database to describe and categorize articles or sources of information based on content. Controlled vocabulary can also be referred to as Subjects, Subject Headings, Subject Terms, Descriptors, Thesaurus, or Index terms. The table on this page outlines the difference between using 'Controlled Vocabulary' and 'Keywords'.
Using a variety of both keywords and controlled vocabulary when searching library databases will help you retrieve the best search results!
| Controlled Vocabulary | Keywords |
| Pre-defined, higher order terminology | Natural (conversational) language |
| Only searches the subject or descriptor field in a database record |
Searches all fields in a database record including title, abstract, text, etc. |
| Results usually relevant to your topic | Results may or may not be relevant to your topic |
| Narrows your search providing fewer results |
Broadens your search providing more results |
| Less Flexible - searches only available, pre-defined subject headings | Flexible - searches newer or distinctive terms and acronyms with no defined subject heading |
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Examples: Canines Skin Neoplasms Hypertension Insomnia |
Examples: Dogs Skin Cancer High Blood Pressure Sleeplessness |