There are many types of open access, perhaps because it is such a young movement that it's still developing standards. That said, there are three basic types:
- Green – refers to self-archiving generally of the pre or post-print in repositories.
- Gold – refers to articles in fully accessible open access journals.
- Hybrid – sometimes called Paid Open Access, refers to subscription journals with open access to individual articles usually when a fee is paid to the publisher or journal by the author, the author's organization, or the research funder. Some of the fees are quite expensive, up to $5000. Some universities or libraries have a pool of funding available for hybrid journal publications or sometimes funding is written into grant applications for open access in hybrid journals. Some examples of hybrid open access are: iOpenAccess by Taylor Francis, Online Open by Wiley, or Sage Open by Sage. For a full list visit Publishers with Paid Options for Open Access from SHERPA/RoMEO.
Though green open access generally refers to the post-print of an article, there are three basic version types that can be self archived in repositories:
- Pre-Prints – The author's copy of article before it’s been reviewed by the publisher, or pre-reviewed.
- Post-Prints – The author's copy of article after it’s been reviewed and corrected, but before the publisher has formatted it for publication, or post-reviewed.
- Publisher’s Version – The version that is formatted and appears in print or online.
If authors have signed a Copyright Transfer Agreement (CTA), the publisher's policy will determine which version of an article can be archived in a repository. Most publishers allow some sort of green open access. Authors can check their CTA for this information. SHERPA/RoMEO is a database of publisher copyright policies and self archiving information that authors can use to check which version they may be allowed to archive. Not all journals are in SHERPA/RoMEO and it isn't always current, so authors may also want to check the publisher's website as well.
SHERPA/RoMEO classifies publishers into colors for easy identification:
- Green - refers to publishers whose policies allow archiving of pre-print and post-print or publisher's version/PDF
- Blue - refers to publishers whose policies allow archiving of post-print or publisher's version/PDF
- Yellow - refers to publishers whose policies allow archiving of pre-print
- White - refers to publishers whose policies do not formally support archiving any version
