Open Access Reference Site

Back to Open Access

What is open access publishing?

Open access is based on the principle that research outputs should be freely and immediately available with reuse rights. When considering open access publishing, there are many dimensions that add to the complexity and can contribute to confusion regarding open access. Points to be aware of are outlined in this section.

Overview of open access publishing

  • "Open access” was first defined in the early 2000s by individual groups meeting in Berlin,1 Bethesda,2 and Budapest.3 These 3 groups defined open access similarly, and their collective definition is often referred to as the BBB definition of open access.

  • At the core of the BBB definition of open access is the principle that research outputs should be available freely (usually via the Internet) and immediately upon publication (without an embargo period) and with minimal restrictions on reuse.

  • Publication of research outputs without cost barriers or copyright restrictions allows others to build on and reuse the research, subject only to the norms of attribution.

  • Authors can choose to submit their manuscript to a dedicated open access journal or select open access options/terms where available in traditional or hybrid journals.

  • Open access options/terms define the degree of availability, archiving, fees, embargo periods, and reuse rights. These options/terms often vary between publishers and can even differ between journals within a single publishing group.

Publishing models

  • Traditional journals

    Traditional journals are subscription based and require a subscription to access published articles or purchase individual articles. Under this publishing model, individual authors transfer copyright to the journal via copyright transfer agreement (CTA). Those wishing to reuse published content must ask permission from the copyright holder, which often requires payment of a fee.

  • Hybrid journals

    Hybrid journals generally require a subscription to access published content, but also offer authors the option of publishing open access for a fee, which is often referred to as an article processing charge (APC).

  • Open access journals

    Open access journals publish articles exclusively under open access licenses, such as CC BY and its derivatives (CC BY-NC, CC BY-ND, CC BY-NC-ND, CC BY-SA), that align with the BBB definition of open access. These journals require an APC for publication. The Directory of Open Access Journals (DOAJ) sets standards for and maintains a list of reputable open access journals.

    • Journals included in the DOAJ must adhere to standards including quality control of published content via peer review, which distinguishes open access journals from predatory journals.

Open access models, repositories, and embargoes

Open Access Options: In general, there are 3 models for archiving open access publications; however, this area is continuing to evolve:

Gold Access Option

Widely used to ensure research outputs are available on terms aligned with the BBB definition of open access, including a CC BY license or derivative (eg, CC BY-NC, CC BY-ND, CC BY-NC-ND, CC BY-SA), and usually requires authors to pay a fee.

Green Access Option

Option that allows authors to self-archive their articles (either the final typeset publication or the submitted version) on personal webpages, institutional webpages, or funder/institutional repositories, often after an embargo with no fee.

Bronze Access Option

Term recently coined by Piwowar et al4 that refers to a long-standing practice where journal editors and publishers make articles that are freely available to read on the journal website, but without a clearly identifiable copyright license. Authors cannot usually choose to publish their manuscript under this model; generally, the decision lies with the journal or publisher regarding which publications to make available on their website and the length of time they will be available.

Publication repositories

  • Authors who are offered a green open access option by the journal need to have a publicly accessible website for storing their publications.

  • Publication repositories fill that need and are a place for articles to be stored and to preserve/provide access to articles.

  • Repositories simply store articles and do not provide services such as editing and peer review.

  • Publication repositories include PubMed Central and university/medical center websites.

  • Funders and institutions often collect their researchers’ works and store them in their own repositories.


In the context of open access, an embargo period refers to the time after an article is published when it is only available to journal subscribers or those who pay to view the publication.

Clarifying copyright

  • Copyright defines how a work can be reused and is most formally defined as the legal protections the copyright holder (either authors or, once a manuscript is published, journals) has to control reuse of their work.

  • Publications aligned with the BBB definition of open access and published with a CC BY license have minimal restrictions on reuse.

  • Many journals have begun to indicate in the front matter of a published article who holds the copyright, what rights are reserved by the copyright holder, and what reuse rights are granted to others.

  • Copyright and license information for a publication is often found under the author byline or at the bottom of the first page of a publication.

  • In the traditional publishing and more restrictive copyright models, the copyright holder (either the author or the journal/publisher) controls all reuse of a work.

Defining reuse rights

Creative Commons licenses are commonly used within the open access space to define for a given publication what rights the copyright holder gives others and what rights they retain. In addition to the formal legal language, Creative Commons licenses include a plain-language summary of the license that is intended to be understandable to those without legal training.

  • Regarding reuse rights, the most generous Creative Commons license is the “CC BY,” or attribution, license, under which works can be freely adapted or reused for any purpose if the original work is cited.

  • The most restrictive Creative Commons license is the “CC BY-NC-ND.” Under this license, non-copyright holders can view the work and distribute it for noncommercial purposes, but they must request permission from the copyright holder to make any adaptions/changes to the work.

  • A Creative Commons license including ShareAlike (SA) terms requires those reusing a given work to license their work on the same terms as the original work, unless the copyright holder grants special permission. SA terms are often added to other Creative Commons licenses. For example, if a work is published with a “CC BY-SA” license, any works that reuse materials from that original work will also need to be published with a “CC BY-SA” license.

  • A work published with a "CC0" license is in the public domain. Under this license, anyone can use a work for any purpose, without citation of the original work.

    • Many journals request that data underlying a manuscript/publication be uploaded to a public data repository/data sharing platform with a CC0 license. Authors should be aware of any journal specific requirements for data sharing, including license requirements.
    • Authors may want to consider sharing their data using a CC BY license. Results in publications shared with a CC BY license can still be reused by anyone for any purpose, however the original data must be cited.

Materials covered by open access terms

When reviewing open access policies, be aware of what materials are considered a part of the article and covered under the article’s copyright. Some journals may have special allowances (or restrictions) for supplemental materials, such as shared data, and/or enhanced content, such as visual abstracts, that accompany an article.

Open access vs open data

Open access policies apply to the published outputs of research (ie, articles). Public availability of the data underlying these articles is determined by open data or data sharing agreements. Journal policies on data availability and sharing are distinct from open access policies.


  1. Berlin Declaration on Open Access to Knowledge in the Sciences and Humanities. 22 October 2003.
  2. Bethesda Statement on Open Access Publishing. 20 June 2003.
  3. Budapest Open Access Initiative. 14 February 2002.
  4. Piwowar H, Priem J, Lariviere V, et al. The state of OA: a large-scale analysis of the prevalence and impact of Open Access articles. PeerJ. 2018;6:e4375. doi: 10.7717/peerj.4375.


Privacy Policy | Contact Us
Copyright © 2011-2020 MPIP. All Rights Reserved.