MeSH is a comprehensive controlled vocabulary for the purpose of indexing journal articles and books in the life sciences; it can also serve as a thesaurus that facilitates searching.
Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed article database and by NLM's catalog of book holdings.
The 2009 version of MeSH contains a total of 25,186 subject headings, also known as descriptors. Most of these are accompanied by a short description or definition, links to related descriptors, and a list of synonyms or very similar terms (known as entry terms).
The descriptors or subject headings are arranged in a hierarchy. The top level categories in the MeSH descriptor hierarchy are:
- Chemicals and drugs
- Analytical, diagnostic and therapeutic techniques and equipment
- Psychiatry and psychology
- Biological sciences
- Physical sciences
- Anthropology, education, sociology and social phenomena
- Technology and food and beverages
- Information science
- Health care
- Publication characteristics
- Geographic locations
Note: a hierarchy is an arrangement of items (objects, names, values, categories, etc.) in which the items are represented as being "above," "below," or "at the same level as" one another and with only one "neighbor" above and below each level. These classifications are made with regard to rank, importance, seniority, power status, or authority.
Abstractly, a hierarchy is simply an ordered set or an acyclic graph.
Wikipedia, the free encyclopedia. Medical subject headings. Internet. Accessed on May 16, 2010.