MEDLINE is the journal citation database of the National Library of Medicine.  It contains biomedical and life sciences references dating back to 1946 garnered from about 5,600 scholarly journals.  MEDLINE is a subset of the PubMed database and a PubMed search can be limited to MEDLINE records using the Journal Categories filter.  Every record in the MEDLINE database has been indexed with the NLM controlled vocabulary, Medical Subject Headings (MeSH).

PubMed, available since 1996, includes the entire MEDLINE database as well as additional citations such as “In-process” citations – records which have not yet been indexed with MeSH vocabulary; “Ahead of Print” citations which precede final publication in a MEDLINE indexed journal; citations for books and some book chapters available on the NCBI Bookshelf, as well as other types of citations.

PubMed Central (PMC) is a database of freely available full-text biomedical and life sciences journal articles.  PMC includes manuscripts which have complied with the NIH Public Access Policy requiring articles that have been supported by NIH funding to be made freely available.  PMC can be accessed via the drop-down menu on the PubMed home page located to the left of the search box.

For further details about these three databases, follow and read the NLM Technical Bulletin on your favorite social media network (use the icons in the upper right hand corner of the screen to choose your outlet).