1. MeSH The Medical Subject Headings from the National Library of Medicine

2. MeSH: U.S. National Library of Medicine Medical Subject Headings Controlled Vocabulary Thesaurus “[C]onsists of sets of terms naming descriptors in a hierarchical structure that permits searching at various levels of specificity.”

3. Structure of MeSH: Descriptors/subject headings (25,000) Terms (160,000) Scope notes Qualifiers

4. Descriptors can appear in more than one place Identified by tree numbers (which may change with each update of the thesaurus) ID numbers (which are permanent)

5. For example, the term “headache” retrieves: 3 tree numbers and their hierarchy Annotations Concepts, both broader and narrower terms

6. MeSH is government authority for health and medicine. GoPubMed uses MeSH as a table of contents to structure search results. GoWeb is attempting to do the same, and incorporates MeSH for non-medical searches, along with other DBs.