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PMC FAQs

Below are answers to many of the questions PMC frequently receives. If you cannot find an answer to your question, please contact the PMC Help Desk at pubmedcentral@ncbi.nlm.nih.gov.

General Interest FAQs

FAQs for Publishers

FAQs for Authors

General Interest FAQs

What is PubMed Central (PMC)?

PubMed Central® (PMC) is a free full-text archive of biomedical and life sciences journal literature at the U.S. National Institutes of Health's National Library of Medicine (NIH/NLM). Learn more about PMC on the About PMC page.

What is the difference between PMC and PubMed?

PubMed is a database of citations and abstracts. PMC is an electronic archive of full-text journal articles, offering free access to its contents. Both resources are scientific literature databases offered to the public by the U.S. National Library of Medicine (NLM).

Does any independent group oversee the operation of PMC?

The National Library of Medicine (NLM) Board of Regents provides oversight of PMC, which is part of the NLM Collection.

The PMC National Advisory Committee also advised on the content and operation of the repository from 1999 through 2017.

What journals are available in PMC? Does PMC contain the complete contents of each journal?

See the PMC Journal List for information about journals that have an agreement with NLM to make the final published version of all articles, or all NIH-funded articles, available in PMC; or are historically-significant journals that have been digitized - see the Digitized Journals in PMC page for more information. PMC also includes select articles from other journals; either submitted through a publisher's Selective Deposit agreement; or as author manuscripts deposited to satisfy a research funder's policy

How far back in time does the archive reach?

PMC has material dating back to the 1780s for some journals. Please visit the Digitized Journals in PMC page for details about NLM's digitization projects.

How can I find out when PMC adds a new journal to the archive?

Use the "Journal added in the last 30 days" filter on the PMC Journal List to see Full Participation and NIH Portfolio journals added in the previous 30 days.

How can I find out about changes to PMC?

PMC-Announce email list: Subscribe to the PMC-Announce email list to be notified by email whenever there are important announcements about PMC.

New in PMC Page/RSS feed: Check the New in PMC/RSS feed for recent PMC developments or features.

How is PMC related to PMC International?

Please see the PMC International page for more information about PMCI.

Are there any restrictions on the use of the material in PMC? Can I download a batch of articles from PMC for research or other purposes?

Systematic downloading of batches of articles from the main PMC website, in any way, is prohibited because of copyright restrictions.

PMC makes three subsets of articles, known as the PMC Article Datasets, accessible through auxiliary services that may be used for automated retrieval and downloading. These services and the datasets are detailed on the PMC Article Datasets page.

The services listed on the PMC Article Datasets page are the only services that may be used for systematic downloading. Do not use any other automated processes for downloading articles, even if you are only retrieving articles from the PMC Article Datasets (including the PMC Open Access Subset).

What is the PMC Open Access Subset? Isn't everything in PMC open access?

The PMC Open Access Subset includes millions of journal articles and preprints that are made available under license terms that allow reuse. Not all articles in PMC are available for text mining or other reuse; many are under copyright. Articles in the PMC Open Access Subset are made available under Creative Commons or similar licenses that allow more liberal redistribution and reuse than a traditionally copyrighted work. The PMC Open Access Subset is one part of the PMC Article Datasets.

What is the NIH Public Access Policy?

Please visit the Public Access Policy section of the NIH Scientific Data Sharing website for more information.

I want to report an error in a PMC article. What do I do?

To report a problem with an article in PMC, please reach out to the NLM Help Desk or email: pubmedcentral@ncbi.nlm.nih.gov.

What does embargo mean and can I get the article anyway?

An embargo is a delay between when an article is published and when the full-text is made freely available in PMC. See the Embargoes section on the PMC Policies page for more information.

Where can I get permissions to reproduce articles or images?

NLM does not hold the copyright for any of the material in PMC and cannot grant permission to reuse or reproduce it. The copyright and license details for any given article can be found under the "Copyright and License information" link on an article record in PMC. For permissions questions, contact the respective journal publisher directly.

For more information, see the PMC Copyright Notice.

See the PMC User Guide for information about how to search for articles by Creative Commons license.

What happens if a journal ceases participation? Will the existing articles be removed?

PMC does not remove articles when a journal ceases participation. The journal's Agreement Status will show as "No longer participating" in the PMC Journal List and all the content deposited previously will remain publicly available.

What is PMC's policy on retractions?

See "Retractions" on the PMC Policies page.

FAQs for Publishers

What are a publisher's options for depositing articles in PMC?

Details about the article submission options available to publishers can be found on the For Publishers page.

Why does PMC require the full-text of every article in XML? Why not accept just a PDF or HTML file?

NLM believes that the best way to ensure the accessibility and viability of digital material over time is through consistent and active use of the archive. PMC stores content in eXtensible Markup Language (XML), which represents the structure and meaning of a document in a relatively simple and human-readable form. All PMC content is converted to and stored in the NISO Z39.96-2015 JATS XML format. This standard format is the most effective and widely used archival format for journal articles.

Who should I contact if there is a change to my journal's title, publication model, or publication frequency?

Please email your PMC Journal Manager with a summary of the change(s), including ISSNs, titles affected, and links to any public announcements about the changes. If there are significant changes to editorial policies, editorial board, or subject matter scope, the publisher will be asked to submit a new application for the journal, in line with PMC's Reevaluation Policy.

How are article citations submitted to PubMed for PMC articles?

Details are available in the PubMed Citations section of the PMC Policies page.

What kinds of usage statistics does PMC provide to participating journals?

Each publisher has password-controlled access to a website that has usage reports for that publisher's journal(s). The reports, updated daily and aggregated by month, include counts of available articles, total access by type of page (e.g., full-text HTML or PDF); count of unique IP addresses; and most frequently retrieved or cited articles. The reports are available for downloaded in CSV or XML format.

Usage data for each individual article is also available in CSV and XML format for a given month.

The usage reports do not include use by specific individuals, organizations or IP addresses, consistent with NLM policies.

PMC usage stats follow COUNTER guidelines on excluding access by robots and crawlers and not counting double clicks. However, PMC is not formally COUNTER compliant because NLM policies do not permit reporting of use by institution. Additionally, PMC statistics do not support some of the access mechanisms, such as SUSHI, or some of the specific report formats.

Participating publishers should contact their PMC Journal Manager for assistance with accessing the statistics website.

What is PMC's policy on accepting articles that are Ahead-of-Print/Online First?

Please see the Online First (OLF) articles entry on the PMC Policies page for information on PMC's policy on accepting articles that are published Ahead of Print/Online First.

FAQs for Authors

I need to have a PMCID for my article, how do I get one?

An article gets a PMCID when the full-text is deposited in PMC, either as the final published version or an author manuscript. For details, please see "Submitting to PubMed Central" in the Public Access Policy section of the NIH Scientific Data Sharing website.

If the final published version is deposited in PMC directly by the publisher, a PMCID will be assigned once the files are successfully processed.

If the author manuscript (i.e., final peer-reviewed version) is submitted to PMC via the NIHMS system, a PMCID will be assigned only after the files have been converted into PMC format, the reviewing author has approved the PMC version, and the NIHMS record has been matched to a PubMed record. Learn more about the manuscript submission process on the NIHMS Overview page.

What is the difference between a PMCID and a PMID?

A Pubmed Central reference number (PMCID) is a unique identifier for full-text article in PMC. A PubMed reference number (PMID) is a unique identifier for a citation record in PubMed. A PMCID is used as evidence of compliance with the NIH Public Access Policy.

What is the relationship between PMC and the NIH Manuscript Submission system?

The NIH Manuscript Submission System (NIHMS) takes in final peer-reviewed manuscripts covered by policies of NIH and other research funders and formats them for inclusion in PMC.

Learn more about NIHMS on the NIHMS Overview page.

I've been told I have to submit my manuscript to PMC, how do I do it?

For information on submitting a manuscript, please see the NIHMS Overview page.