Open Access Publishing

The different models of open access publishing are conventionally referred to by a color naming system.

Green OA: Green open access refers to the practice of making a version of a scholarly article available in an institutional or subject repository, or on a personal website. This is known as self-archiving. The deposited version can be either the preprint (before peer-review) or the postprint (after peer-review, but before publisher's formatting). This type of open access usually does not involve payment of any fees to the publisher.

Gold OA: Gold open access refers to articles that are made freely available by the publisher immediately upon publication. In this model, the publisher bears the cost of publishing and the article is made available to readers at no cost. To cover the costs of publishing, the author or their institution usually pays an article processing charge (APC). The APC can range from a few hundred to a few thousand dollars, depending on the journal.

Hybrid OA: Hybrid open access refers to journals that offer both subscription-based access to articles as well as the option for authors to pay an APC to make their individual articles openly available. In other words, the journal offers a hybrid model where some articles are only available to subscribers while others are available to all readers. This allows publishers to continue generating revenue from subscriptions while also providing authors with an option to make their work open access. However, this model has been criticized for its high APCs and lack of transparency regarding how the funds are being used by publishers.

Bronze OA: Bronze open access refers to articles that are made available for free on the publisher's website, but without any open license. This means that the articles are free to read but cannot be reused or redistributed without permission from the publisher or author. Bronze open access is often used by publishers as a way to increase the visibility of their content and attract more readers.

Diamond or Platinum OA: This refers to journals that are entirely funded by non-profit organizations or universities, and do not charge authors any APCs to publish their articles. These journals are often run by volunteers and rely on the support of the academic community to cover their operating costs. Diamond open access journals are considered to be a more sustainable and equitable model of open access, as they do not place any financial burden on authors or readers. However, they may have lower visibility and impact compared to established commercial journals.