PubMed Central

PubMed Central (PMC) is a free digital repository that archives open access full-text scholarly articles that have been published in biomedical and life sciences journals. As one of the major research databases developed by the National Center for Biotechnology Information (NCBI), PubMed Central is more than a document repository. Submissions to PMC are indexed and formatted for enhanced metadata, medical ontology, and unique identifiers which enrich the XML structured data for each article. Content within PMC can be linked to other NCBI databases and accessed via Entrez search and retrieval systems, further enhancing the public's ability to discover, read and build upon its biomedical knowledge.

PubMed Central is distinct from PubMed. PubMed Central is a free digital archive of full articles, accessible to anyone from anywhere via a web browser (with varying provisions for reuse). Conversely, although PubMed is a searchable database of biomedical citations and abstracts, the full-text article resides elsewhere (in print or online, free or behind a subscriber paywall).

PubMed Central began as E-biomed, initially proposed in May 1999 by then-NIH director Harold Varmus. The idea came to him "abruptly" in December 1998, inspired by the early use of arXiv for preprints after a presentation from Pat Brown of Stanford and David Lipman, director of NCBI:

But my views broadened abruptly one morning in December of 1998 when I met Pat Brown for coffee, at the café that was formerly the famed Tassajara Bakery, on the corner of Cole and Parnassus, during a visit to San Francisco. [...] A few weeks before our coffee, Pat had learned about the methods being used by the physicist Paul Ginsparg and his colleagues at Los Alamos to allow physicists and mathematicians to share their work with one another over the Internet. They were posting "preprints" (articles not yet submitted or accepted for publication) at a publicly accessible website (called LanX or arXiv) for anyone to read and critique. [...] The more I thought about this, the more I was convinced that a radical restructuring of methods for publishing, transmitting, storing, and using biomedical research reports might be possible and beneficial. In a spirit of enthusiasm and political innocence, I wrote a lengthy manifesto, proposing the creation of an NIH-supported online system, called E-biomed.

The goal of E-biomed was to provide free access to all biomedical research. Papers submitted to E-biomed could take one of two routes: either immediately published as a preprint, or through a traditional peer review process. The peer review process was to resemble contemporary overlay journals, with an external editorial board retaining control over the process of reviewing, curating, and listing papers which would otherwise be freely accessible on the central E-biomed server. Varmus intended to realize the new possibilities presented by communicating scientific results digitally, imagining continuous conversation about published work, versioned documents, and enriched "layered" formats allowing for multiple levels of detail.

The proposal to create a central index of biomedical research was a radical departure from prevailing publishing norms. Prior to the internet, publication indexes operated largely like ISBNs: allocated by registration agencies to secondary publishers. The idea that anyone could own their own address space via a domain name and create their own indexing system was a wholly new idea. Major commercial publishers had begun experimenting with an indexing system for scientific papers shared across publishers as early as 1993, and were spurred to action following the E-biomed proposal. At the October 1999 STM Annual Frankfurt Conference, several publishers led by Springer-Verlag reached a hurried conference room consensus to launch their competitor prototype:

At the Board meeting of the STM association, held the afternoon of Monday, October 11, before the fair's Wednesday opening, discussion focused on an emerging U.S. National Library of Medicine (NLM) initiative called E-Biomed (later PubMed Central) that had been proposed by Harold Varmus of the National Institutes of Health in the spring of 1999. Varmus envisioned a digital archive of journals, accessible free of charge and with the added value of reference linking. "Our consensus was that publishers should be the ones doing the linking," said Bob Campbell, who chaired the meeting. "Since we were 'higher up the stream,' so to speak, we should be able to link our articles ahead of the NLM as part of the process of producing them. Stefan von Holtzbrinck then set the ball rolling by offering to link Nature publications with anyone else's. We decided to issue an announcement of a broad STM reference linking initiative. It was, of course, a strategic move only, since we had neither plan nor prototype."

A small group led by Arnoud de Kemp of Springer-Verlag met in an adjacent room immediately following the Board meeting to draft the announcement, which was distributed to all attendees of the STM annual meeting the following day and published in an STM membership publication. [...] The potential benefit of the service that would become CrossRef was immediately apparent. Organizations such as AIP and IOP (Institute of Physics) had begun to link to each other's publications, and the impossibility of replicating such one-off arrangements across the industry was obvious. As Tim Ingoldsby later put it, "All those linking agreements were going to kill us."