Models of OA: Green and Gold
There are two major models for Open Access publishing, Green and Gold.
*Diagram by Foster Open Science (PASTEUR4OA) illustrating the two models of Open Access, Green and Gold.
Green Open Access is typically sharing a non-final version of the material (preprint and postprint). These versions may be shared on certain websites or repositories, sometimes after an embargo period. It may also be referred to as self-archiving. Not all publishers allow "green" open access, and there may be additional restrictions in publishing contracts that limit what, when, and where the works may be shared. Check Sherpa/Romeo for individual journal policies.
Green (OA)--Finding repository based Open Access:
Gold Open Access typically allows sharing and access to the final version of the work, which is often placed under a Creative Commons license. Some, but not all, publishers may require an article or book processing fees in order to make a work open access. This fee may be covered by the author or their department, library, institution, funder, etc., on behalf of the author.
Finding Gold (OA) publishers: Open Access may, or may not, have some processing fees.
Find Open Access journals through DOAJ.
When searching in DOAJ, you can use a filter to search for journals "without article processing charges (ASPCs)"
Directory of Open Access Books (DOAB).
This video by SHB Online breaks down the differences between Green and Gold models, as well as the various Creative Commons license distinctions used for Open Access publishing.