Controlled vocabulary--also known as subject headings, subject terms, thesaurus terms, or descriptors--are the official indexing terms used by the producers of a database to describe each concept so that all articles/items on the same topic have the same descriptor or subject heading.
In contrast to Google searching on the web, controlled vocabularies organize the information in a database. Each article record is divided up into fields, and one of the fields is for subject headings. You can then search on this field. You can also click on a subject heading assigned to an article to see all the other items that have the same heading. You can also combine the terms in a new search to find items on that topic.
Your search results will be more focused and more relevant, since you will be searching directly in the descriptor field.
