PMID (PubMed ID) is the unique identifier for a publication's abstract in PubMed.
PMCID (PubMed Central ID) is the unique identifier for a free complete article (once it is publicly available) in PubMed Central.
PubMed and PubMed Central, produced by the U.S. National Library of Medicine, are text archives of biomedical and life sciences literature.
A DOI (Digital Object Identifier) is a publisher’s unique identifier for a publication. The prefix http://dx.doi.org/ is presumed. Publishers may charge for access.
Department of Health and Human ServicesNational Institutes of HealthU.S. National Library of Medicine
Lister Hill National Center for Biomedical CommunicationsU.S. National Library of Medicine8600 Rockville Pike, Bethesda, MD 20894301-496-4441
NIH…Turning Discovery Into Health