GREEN

Green Open Access is self-archiving by the author. The author makes some version of the publication freely available by way of depositing it in an institutional or a discipline-based repository, or by uploading it to the author’s own homepage.

Such self-archiving always take place in compliance with the contract signed between the author and the publisher. Publishers typically allow some kind of self-archiving (Green OA). The final published version of the manuscript usually cannot be self-archived, however, preprint or postprint versions in most cases can be, sometimes with a certain predefined time lag (embargo period). The embargo period is typically one year from the date of publishing. Some publishers require a shorter embargo period and some other publishers do not require an embargo period at all.

• Preprint: the version submitted to the journal (a version prior to peer review and acceptance)
• Postprint:  the version which has been accepted for publication, it includes revisions made by the authors in response to the peer review process. A postprint differs from the final published version in that it had not been subject to copyediting by the publisher.
• Embargo: a temporary limit on free access. Some journals require that the publication be only made freely available after a certain amount of time (the embargo period) has passed since publishing. Embargo lengths vary, the most typical is one year.

Authors should acquaint themselves with the archiving policies of publishers. The website SHERPA/RoMEO provides an overview of the policies of the major publishers. Information can also be found on the homepages of the individual publishers.
 

GOLD

Gold Open Access is the publication of scientific articles in open access journals. (I.e., journals which provide free access to all of their articles.) In this case, the article will be accessible on the journal’s webpage. Some publishers require that the authors of an accepted manuscript pay an article processing charge (APC) before publication.

APC (Article Processing Charge): At certain open access publications, publishing costs need to be covered by the published authors in the form of an article processing charge. (In practice, it is typically the university or research institute with which the author is affiliated that pays the charge.)
 

PLATINUM / DIAMOND

Diamond Open Access is the publication of scientific articles in open access journals which do not charge an APC.
 

HYBRID

Hybrid access covers the practice of certain traditional, subscription-based non-open-access journals, where it is possible for authors to pay in order for their particular article to be made freely available. This means, however, that while that particular article becomes freely available, all the other articles in the same issue continue to be available only to subscribers. Hybrid journals in effect collect both traditional subscription fees and also payments from authors who wish to make their articles freely available.