Open access (OA) journals are scholarly journals that are available online to the reader "without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself." They remove price barriers (e.g. subscription, licensing fees, pay-per-view fees) and most permission barriers (e.g. copyright and licensing restrictions). While open access journals are freely available to the reader, there are still costs associated with the publication and production of such journals. Some are subsidized, and some require payment on behalf of the author.
Some open access journals are subsidized and are financed by an academic institution, learned society or a government information center. Others are financed by payment of article processing charges by submitting authors, money typically made available to researchers by their institution or funding agency. Sometimes these two are referred to respectively as "gold" and "platinum" models to emphasize their distinction, although other times "gold" OA is used to refer to both paid and unpaid OA.
In 2009, there were approximately 4,800 active open access journals, publishing around 190,000 articles. As of October 2015, this had increased to over 10,000 open access journals listed in the Directory of Open Access Journals,though this number has fallen to 9,500 in January 2017. A study of random journals from the citations indexes AHSCI, SCI and SSCI in 2013 came to the result that 88% of the journals were closed access and 12% were open access.