PubMed, developed by the National Centre for Biotechnology Information (NCBI) at the (US) National Library of Medicine (NLM), is a free database of citations to more than 16 million journal articles from over 4,600 of the world's most significant health sciences journals. These citations are to articles in journals in the fields of medicine, nursing, dentistry, veterinary medicine, health care systems, and the life sciences.
A list of the journals covered is available here.
The database consists primarily of citation-only references, but in some cases the LinkOut feature provides access to full-text articles at journal websites and in other web resources. PubMed includes links to most of the (full-text) articles in PubMed Central.
The bibliographic information in PubMed includes MEDLINE, but also includes additional material such as citations that precede the date a journal was selected for Medline indexing. For information on the difference between PubMed and MEDLINE, see the NLM Fact Sheet: What's the Difference Between MEDLINE and PubMed?
PubMed includes a journals database, which can be searched in various ways, and the My NCBI feature, which allows for saving results and searches and for setting up alerts.
Coverage extends back to the 1950s; the database is updated weekly.