Gold OA

OA through journals, regardless of the journal’s business model. Also see Green OA.

Gratis OA

Access that is free of charge but not necessarily free of copyright and licensing restrictions. Also see Libre OA.

Green OA

OA through repositories. Also see Gold OA; Repository; Self-archiving.

Libre OA

Access that is both free of charge (gratis OA) and free of at least some copyright and licensing restrictions. Because there are many possible copyright and licensing restrictions, libre OA is not just one access model but a range of access models. All the degrees of libre OA are alike in permitting uses that exceed fair use (or the local equivalent). Also see Gratis OA; License.


A statement from a copyright holder telling users what they may and may not do with a copyrighted work. Open licenses, such as those from Creative Commons, permit different degrees of libre OA. In the absence of an open license, a copyrighted work is under an all-rights-reserved copyright, its users may not exceed fair use (or the local equivalent), and OA is at most gratis OA. Also see Gratis OA; Libre OA.

Open access (OA)

Barrier-free access to online works and other resources. OA literature is digital, online, free of charge (gratis OA), and free of needless copyright and licensing restrictions (libre OA). The term was introduced by the Budapest Open Access Initiative in February 2002.

Publication fee

Sometimes called a processing fee and sometimes (erroneously) an author fee. A fee charged by some OA journals when accepting an article for publication, in order to cover the costs of production. It’s one way to cover production costs without charging readers and erecting access barriers. While the bill goes to the author, the fee is usually paid by the author’s funder or employer, not by the author out of pocket.


In the world of OA, a repository is an online database of OA works. Repositories don’t perform their own peer-review, but they may host articles peer-reviewed elsewhere. In addition, they frequently host unrefereed preprints, electronic theses and dissertations, books or book chapters, datasets, and digitized print works from the institution’s library. Institutional repositories aim to host the research output of an institution, while disciplinary or central repositories aim to host the research output of a field.


Also called OA archiving. The practice of making work OA by depositing it in an OA repository. Also see Green OA.

Toll access (TA)

Access limited to those who pay. The most generic term for the opposite of OA.