Subject headings are a "controlled vocabulary," an authoritative list of terms assigned by the database to organize resources.
The most common subject headings are created and maintained by the Library of Congress (Library of Congress Subject Headings). Most databases use LCSH to organize resources. Medical and health sciences literature is organized using Medical Subject Headings (MeSH). Databases may also have their own controlled vocabulary, or thesaurus, of terms.
To search by subject headings:
This helpful demonstration shows how to use the thesaurus to craft a search. You can save searches and set up automated search alerts in PsycINFO and in most databases by setting a personal account in the database.