Open Access

What is Open Access?

Open Access means that a formal research output is available online to read and to reuse, free of most copyright restrictions. Efforts to make more research outputs available have been gathering pace, starting in the late 1990s, with increasing requirements from funders, governments and institutions over the past two decades, changes in publishing business models, and adoption of greater sharing by researchers.

There are broadly two ways in which a research output can be made more accessible and these are categorised based on where the accessible copy is. The publisher may make the final formal version available on their website (or their main hosting platform). Some journals are completely accessible, with every article being available, and some have a mixed model where some articles are accessible but others are only available to subscribers. Publishers also sometimes make articles accessible for a limited time or without any explicit re-use rights. This doesn’t qualify as “open access” because permanent access is not guaranteed. We call access through the publisher “Publisher Open” and divide this into “OA Journal”, “Hybrid” and “No Guarantees”. Publisher Open has traditionally been labelled as “Gold OA” but this label is so inconsistently applied (sometimes being used for OA Journals only, sometimes including hybrid) that we avoid it. The “No Guarantees” category is often referred to as “Bronze” which we avoid here for similar reasons.

The second mode for open access is where a copy of the article is made available through a platform other than the publisher. We call this “Other Platform Open”. The article copy might be the final published and formatted version, the authors final manuscript after peer review, the submitted version or a preprint. It might be placed in an institutional repository, a disciplinary repository, a preprint repository or a general repository infrastructure. As long as the repository meets certain standards for inclusion, relating to reliability, technical capacity and preservation, all of these qualify for our analysis. This category is sometimes referred to as “Green OA” but again there is confusion about how this applied so we avoid the term. We do provide information on which repositories a copy is found in and what we can say about the version of that copy.

Note that any given article can be either Publisher Open or Other Platform Open, both of these, or neither. Many other analyses only count Other Platform Open (“Green”) when an article is not Publisher Open (“Gold”). We separate these categories to emphasise that both are independent and valid pathways to making articles accessible with their own benefits for authors. Understanding both pathways independently is useful in identifying where to focus resources and effort to increase accessibility.

Finally, we define an article as “Accessible” if it is either Publisher Open, Other Platform Open, or both. Closed publications are simply publications that do not qualify as accessible.

See the flowchart below to determine the type of open access for a publication.

Why is Open Access important?

Out of 42 million journal articles and conference papers published since 2010, 47% are accessible in some form and more than 53% are Closed! This means that academics and institutions that cannot afford to subscribe to expensive Subscription Journals will struggle to read 53% of papers published in the last 10 years. Not to mention the general public, businesses, and people in developing nations.

Access benefits the authors of publications, the institutions to which they belong, and research as a whole. As an author, this publication model benefits you because there are no barriers to your potential audience. Institutions can also improve their visibility, increasing their exposure and influence. Open Access is advantageous to science and the global community since it allows everyone to study academic research, even people who might otherwise be unable to afford subscription journals. And most important of all, giving the entire globe instant access to current knowledge allows science to advance even quicker.

What can we do about it?

The good news is that we can all contribute to improving the situation! There are a few options to explore depending on your situation.

  1. If you're an author of previous work, you can go back and upload copies of your previous Closed publications to your institution's library repository or other public repositories to make them Other Platform Open.
  2. If you are involved in the development of new research, consider Open Access Publishers, Journals, or Proceedings when considering a publication venue. If a decent choice isn't available yet, consider the best possibilities for preprint servers in your field of study, or have a strategy in place for placing a copy onto a publicly accessible repository in parallel to publishing through a regular source.
  3. If you aren’t publishing research yourself, but have an interest in accessing published research, keep in mind that the majority of it is funded entirely or partially by public funding. Consider taking a proactive approach to bringing this issue to light. Support open access advocates by raising the issue of access and tell stories of how you have benefited from access to research outputs, or frustrations where you have not been able to.

Open Access categories

Table 1 describes the Open Access categories used in the index tables, including Publisher Open, Other Platform Open and Closed Access.

Publisher OpenAn article published in an Open Access Journal or made accessible in a Subscription Journal.The final edited publication can be read directly from the publisher's website, usually immediately on publication (for OA Journal or Hybrid).The sum of Gold, Hybrid and Bronze.
Other Platform OpenThe publication was shared online; on a preprint server, a university library repository, domain repository or an academic staff page.Can be applied to existing articles that are already published as well as new articles. Generally without any cost.Green and Grey.
ClosedA publication that is not either Publisher Open or Other Platform Open.To increase access to academic research, these are the publications that should be focused on to make accessible by uploading an appropriate copy to a public repository.Not Open, Closed or Closed Access.

Table 1. Open Access categories.

Table 2 provides a breakdown of the Publisher Open categories, as shown in the charts on institution and country details pages.

OA JournalPublished in an Open Access Journal.To qualify as an OA journal there must be clear re-use rights and certain quality measures need to be validated by the Directory of Open Access Journals.
HybridMade accessible in a Subscription Journal with an open license.A route to making articles available in older journals that were historically subscription based and have not transitioned to fully open access. Almost always involves payment of an APC or some form of institutional payment through a “read and publish” agreement.
No GuaranteesMade accessible in a Subscription Publisher with no reuse rights.Publishers sometimes make articles available for limited periods or without guarantees. This makes more articles readable but doesn’t ensure long term accessibility.

Table 2. Publisher Open categories.

Table 3 provides a breakdown of the Other Platform Open categories, as shown in the charts on institution and country details pages.

InstitutionPublications placed in institutional repositories, which are archives for storing and distributing an institution's research outputs. Includes repositories shared amongst multiple institutions.Institutions can take responsibility for archiving their own materials, ensure their own awareness of research outputs, and leverage institutional policies including rights retention approaches.
PreprintPublications deposited on servers that do not make claims about formal peer review. Generally non-peer reviewed manuscripts, including working papers on platforms such as arXiv, bioRxiv, SSRN, RePec etc.In many disciplines preprints or working papers are a major mode of dissemination. Using preprint servers also enables post-release peer review and often offers an alternate route to increasing access which is easier than for formally published versions.
DomainPublications from domain repositories, also known as disciplinary or subject repositories. A domain repository contains publications from a specific subject area. Examples include PubMed Central, Europe PMC and Econstor.The large domain repositories with the roots in biomedical sciences, Pubmed Central and Europe PMC are major drivers of access, often linked to their use within the policy requirements for funders that were early movers on open access.
PublicPublications from repositories that can be used by researchers from any domain and to deposit any form of output, including pre-prints, published manuscripts and datasets. Semantic Scholar, Figshare and Zenodo are a few examples.Free and public repositories are an increasing medium for the release of research materials including those beyond the traditional research paper. Where they are used specifically for providing access to formally published (or intended to be published) materials they can be used to host both pre-peer review manuscripts (“preprints”) or post review manuscripts.
Other InternetOutputs on sites we have not classified. In practice these are copies identified by CiteSeer X which is in turn indexed by Unpaywall. It may include publications on academic staff pages, blogs and social networks. We do not directly track outputs on platforms such as and is still common for outputs to be placed in many places. These sources are generally not archived or reliable for the long term so we do not count them in the more reliable categories of platform.

Table 3. Other Platform Open categories.