Open access (OA) refers to research outputs which are distributed online and free of cost or other barriers, possibly with the addition of a Creative Commons license to promote reuse.
Academic articles (as historically seen in paper-based academic journals) have been the main focus of the movement. Conventional (non-open access) journals cover publishing costs through access tolls such as subscriptions, site licenses or pay-per-view charges. Open access can be applied to all forms of published research output, including peer-reviewed and non peer-reviewed academic journal articles, conference papers, theses, book chapters, and monographs.