A guide to information literacy and library skills for NHS staff from Trusts supported by UCL Library Services, to inform clinical practice, study and research.
Subject headings are similar to tags or hashtags. They describe the topic of an item in a database.
However, unlike tags they come from an official, standardized set of terms and are assigned by experts.
The index of subject headings is usually called the Thesaurus.
Many resources have their own list of subject headings, or thesaurus. For example, the database Medline has a thesaurus called MeSH (Medical Subject Headings).