PubMed Central is a free digital archive of biomedical and life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM). With PubMed Central, NLM has taken the lead in preserving and maintaining access to the electronic literature, just as it has done for decades with the printed biomedical literature. PubMed Central aims to fill the role of a world class library in the digital age. It is not a journal publisher. NLM believes that giving all users free access to the material in PubMed Central is the best way to ensure the durability and utility of the archive as technology changes over time.

PubMed Central follows in the footsteps of other highly successful and useful services that NCBI has developed for the worldwide scientific community: GenBank, the genetic sequence data repository, and PubMed, the database of citations and abstracts to biomedical and other life science journal literature. GenBank, and the tools provided by NCBI for searching and manipulating its contents, have been a boon to molecular biologists and have helped advance developments in the field. PubMed (which encompasses Medline) is the database of choice, for researchers and clinicians alike, to locate relevant articles and, in many cases, link directly to a publisher's site for the full text.

Participation by publishers in PubMed Central (PMC) is voluntary, although participating journals must meet certain editorial standards. (See How to Join PMC.) Journals are encouraged to deposit all their content (and not just research papers or other selected material) in PMC so that the archive becomes a true digital counterpart to NLM's extensive collection of print journals. In line with this objective, NLM has digitized earlier print issues of many of the journals that are in PMC. Although immediate free access to all content is most desirable, a journal may delay release of its full text in PMC for some period of time after publication. See the Deposit and Access Policies for more information.

A journal is guaranteed access to a copy of its deposited data upon request, at no cost. PubMed Central does not claim copyright on any material deposited in the archive. Copyright remains with the journal publisher or with individual authors, whichever is applicable.

The value of PubMed Central, in addition to its role as an archive, lies in what can be done when data from diverse sources is stored in a common format in a single repository. GenBank has proven the advantages of collecting DNA sequences in a central repository with a common format. You get more rapid searching, manipulation, and cross-linking of the complete collection, and all the benefits that derive from that. Similarly, with PubMed Central, one can quickly search the entire body of full-text articles and locate relevant material regardless of its source. It also makes it possible to integrate the literature with a variety of other information resources such as sequence databases and other factual databases that are available to scientists, clinicians and everyone else interested in the life sciences. The intentional and serendipitous discoveries that such links might foster excite us and stimulate us to move forward.

Most journals now have online publishing operations and there is a growing tendency to publish material online only, to the exclusion of print. This literature must be preserved in a form that ensures unrestricted access to it over the longer term. This is what NLM has undertaken to do. We invite all journals to join those that have already committed to creating this resource for people all over the world.