Unrestricted access to, and reuse of, published journal articles benefits the research community by facilitating the dissemination of new information, thus maximizing opportunities for that work to lead to new insights and discoveries.
(From Developing a Toolkit for Fostering Open Science Practices: Proceedings of a Workshop which is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0))
Quite simply, Gold OA is open access facilitated by a publisher. But just because there's "gold" in the name doesn't make it the best or only way to make your research open. How you decide to share your research will depend on many factors, including who is funding your grant, the nature of your research, your career goals, the norms of your department and academic discipline, your personal thoughts about sharing your work, and a host of other factors. See Transformative Agreements for more on the UI Libraries' role in facilitating Gold OA.
While Gold OA is always publisher facilitated, there are different ways they make work open. Here are the basic models that publishers follow:
“Green OA” is often called "self-archiving" by publishers and refers to author-initiated open access. Authors can make their work open access by posting an article after publication in an open repository or by posting an unpublished article on a preprint server or other repository. One advantage to choosing Green OA instead of Gold is that there is no cost associated with self-archiving and sharing your work, as there often is when making your research OA through a publisher. Pre-prints and accepted manuscripts are the two most common article versions made available through Green OA.
A preprint is a manuscript that has not yet been submitted to a journal, and may never be. These manuscripts are submitted to a disciplinary preprint server, where they are freely available and are open for comments. Preprints allow for rapid dissemination of new research and the feedback received can strengthen the manuscript. Many preprint servers allow authors to incorporate feedback into the manuscript, before it is submitted for publication in a journal. Readers need to be clear that because preprints do not undergo peer review, conclusions may have changed prior to publication. Preprints may also be called Submitted Version, Author's Original Manuscript (AOM), or Original manuscript.
The accepted version is the final author-created version of a manuscript that has been accepted for publication and incorporates referee comments made during peer review. However, it may lack final copy-editing and does not incorporate the journal’s layout or pagination. It is also known as: Authors Accepted Manuscript (AAM), Authors accepted version, Final Author version, and Post-print. Publishers may allow these to be shared through a disciplinary repository or an institutional repository, but often after an embargo period has passed.