Open Access

Open access refers to the practice of making scholarly research publications freely available online so that anyone can read, download, copy, distribute, and use them without financial, legal, or technical barriers. Open access removes the traditional paywall model in which readers or their institutions must pay subscription fees to access published research.

Open access has transformed the landscape of scholarly communication by addressing one of the most persistent barriers to knowledge dissemination: cost. Under the traditional subscription model, many researchers, clinicians, students, policymakers, and members of the public are unable to access research findings because their institutions cannot afford journal subscriptions. This is particularly acute in low and middle income countries and at smaller institutions. Open access removes this barrier, enabling global participation in science and accelerating the pace of discovery. Many studies report that open access articles are read and cited more than paywalled articles, although the size of this citation advantage, and how much of it open access itself causes, remain debated. Major funders including the National Institutes of Health, Wellcome Trust, and European Research Council now mandate that research they fund be made openly available, recognizing that publicly funded research should be publicly accessible.

Open access operates through several distinct models. Gold open access means the final published version of an article is immediately and freely available on the journal's website, typically under a Creative Commons license. The costs of publication are often covered by article processing charges (APCs) paid by authors or their institutions rather than by reader subscriptions. Some gold open access journals charge no APCs and are funded through institutional subsidies, society support, or volunteer labor.

Green open access (also called self archiving) allows authors to deposit a version of their manuscript, usually the accepted manuscript after peer review but before final formatting, into an institutional or subject repository. The published version remains behind the journal's paywall, but the repository copy is freely accessible. Many traditional journals permit green open access after an embargo period, commonly between six and twenty four months depending on the publisher and field, although some funder policies, such as the 2024 NIH Public Access Policy, now require the accepted manuscript to be available with no embargo.

Hybrid open access journals are subscription based publications that offer authors the option to pay an APC to make individual articles open access while the rest of the journal content remains behind a paywall. This model has been criticized for "double dipping," in which publishers receive both subscription revenue and APCs.

Diamond (or platinum) open access journals charge no fees to either authors or readers and are typically funded by academic institutions, scholarly societies, or government grants. Preprint servers such as arXiv, bioRxiv, and medRxiv provide immediate open access to manuscripts before formal peer review, and have become increasingly important for rapid dissemination.

The licensing framework is a critical component of open access. Creative Commons licenses are widely used for open access, and CC BY (allowing any use with attribution) is the license that policies such as Plan S, the cOAlition S funders' policy, prefer. Different license variants offer varying levels of restriction on commercial use, derivatives, and redistribution.

Choose open access publication routes when your funder mandates it, when you want to maximize the visibility and impact of your work, or when your research addresses topics of broad public interest where restricting access would be particularly harmful. Consider green open access through institutional repositories when gold open access APCs are unaffordable and your publisher's policy permits self archiving.

A common mistake is assuming that all open access journals are low quality or predatory. In reality, many highly regarded journals, such as PLOS Medicine, eLife and Nature Communications, are open access. Researchers should judge a journal by its peer review practices, editorial transparency and indexing in major databases, such as the Directory of Open Access Journals (DOAJ) for open access titles, rather than by whether it is open access. Another mistake is failing to check funder mandates for open access, potentially resulting in noncompliance with grant conditions. Some researchers also overlook the option of green open access through institutional repositories, which requires no payment and is permitted by many publishers. Finally, neglecting to specify an appropriate Creative Commons license can inadvertently restrict the reuse potential of open access publications.

A biomedical researcher funded by the NIH completes a clinical trial and prepares the manuscript for publication. Under the 2024 NIH Public Access Policy, which applies to manuscripts accepted for publication on or after July 1, 2025, the author accepted manuscript must be submitted to PubMed Central on acceptance and made publicly available there with no embargo, by the article's official publication date. The researcher chooses to submit to a gold open access journal that charges a $2,500 APC, which is covered by the grant budget. On publication, the article is immediately freely available worldwide with a CC BY 4.0 license. The researcher also deposits the accepted manuscript in their university's institutional repository, ensuring a second point of access.