There are many types of open access journals, and they fall into different publishing models:
- Gold – publisher makes to articles in fully accessible on the journal website, under a creative commons or similar license. An APC is usually paid by the author (or other funder).
- Hybrid – a subscription journal where the publisher allows authors to pay to make individual articles open access. Differs from a Gold OA journal because a library (or other subscriber) is still paying for a subscription to the journal, so effectively, the publisher is paid twice for the article, once via subscription, and once via the APC to make the article OA.
- Diamond/Platinum - journals that publish OA but do not charge APCs. These are funded by institutions, advertising, philanthropy, etc.
- Bronze - journals that are free to read online but do not have a license - they are not generally available for reuse.
- Green – refers to self-archiving generally of the pre or post-print of articles in repositories.
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), 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.