MeSH: Medical Subject Headings Vocabulary

MEDLINE uses a controlled vocabulary, meaning that there is a specific set of terms used to describe each article. Familiarity with this vocabulary will make you a better PubMed searcher.

MeSH vocabulary is organized by 16 main branches:

1. Anatomy
2. Organisms
3. Diseases
4. Chemical and Drugs
5. Analytical, Diagnostic and Therapeutic Techniques and Equipment
6. Psychiatry and Psychology
7. Biological Sciences
8. Natural Sciences
9. Anthropology, Education, Sociology and Social Phenomena
10. Technology, Industry, Agriculture
11. Humanities
12. Information Science
13. Named Groups
14. Health Care
22. Publication Characteristics
26. Geographic Locations 

NLM indexers examine articles and assign the most specific MeSH heading(s) that appropriately describes the concept(s) discussed. Every drug and chemical MeSH heading has been assigned one or more headings that describe known pharmacological actions (PA).