The How PubMed Works: Medical Subject Headings (MeSH) materials addresses increasing health information access and use by highlighting features of the National Library of Medicine’s PubMed bibliographic database. Content last updated November 2025. This resource is supported by the National Library of Medicine (NLM), National Institutes of Health (NIH) under cooperative agreement number UG4LM013732 with the University of Utah’s Spencer S. Eccles Health Sciences Library. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. If you have any questions, please reach out to nto@nnlm.gov.