Open Access

Open access (OA) is the practice of providing unrestricted access via the Internet to peer-reviewed scholarly journal articles. OA is also increasingly being provided to theses, scholarly monographs and book chapters.

Open access comes in two degrees: Gratis OA is no-cost online access, while Libre OA is Gratis OA plus some additional usage rights.

Open content is similar to OA, but usually includes the right to modify the work, whereas in scholarly publishing it is usual to keep an article's content intact and to associate it with a fixed author or fixed group of authors. Creative Commons licenses can be used to specify usage rights. The open access idea can also be extended to the learning objects and resources provided in e-learning.

OA can be provided in two ways:

Green OA Self Archiving

Authors publish in any journal and then self-archive a version of the article for free public use in their institutional repository, in a central repository (such as PubMed Central), or on some other OA website. What is deposited is the peer-reviewed postprint – either the author's refereed, revised final draft or the publisher's version of record. Green OA journal publishers endorse immediate OA self-archiving by their authors. OA self-archiving was first formally proposed in 1994 by Stevan Harnad. However, self-archiving was already being done by computer scientists in their local FTP archives in the '80s, later harvested into Citeseer. High-energy physicists have been self-archiving centrally in arXiv since 1991.

Gold OA Publishing

Authors publish in an open access journal that provides immediate OA to all of its articles on the publisher's website. (Hybrid open access journals provide Gold OA only for those individual articles for which their authors (or their author's institution or funder) pay an OA publishing fee.) Examples of OA publishers are BioMed Central, the Public Library of Science, and Dove Medical Press.

Public access to the World Wide Web became widespread in the late 1990s and early 2000s. The low-cost distribution technology has fueled the OA movement, and prompted both the Green OA self-archiving of non-OA journal articles and the creation of Gold OA journals. Conventional non-OA journals cover publishing costs through access tolls such as subscriptions, site-licenses or pay-per-view. Some non-OA journals provide OA after an embargo period of 6–12 months or longer (see Delayed open access journals). Active debate over the economics and reliability of various ways of providing OA continues among researchers, academics, librarians, university administrators, funding agencies, government officials, commercial publishers, editorial staff and society publishers.