Medical Subject Headings (MeSH) is the name of the controlled vocabulary and thesaurus used for indexing articles in PubMed. Each article indexed in PubMed has MeSH terms applied, so that those searching with MeSH terms can expect to find every article in PubMed about a specific topic, regardless of the wording used by individual authors. For more instruction on searching using MeSH, see these tutorials. MeSH is maintained by the National Library of Medicine and serves as as a reliable, updated thesaurus of medical terminology. It is often re-used as an indexing language in other resources such as ClinicalTrials.gov or library catalogs.