Open access is a term describing an information resource that is open to all.
It also refers to a movement within the academic community dedicated to making scholarly research more accessible, rather than hidden behind a price or permission barriers.
“Open access” journals are not necessarily free, since they may charge a fee for maintenance costs, or to compensate authors, but typically an open access resource is free to all to read and use. Journals that ask for some payment are sometimes called “hybrid” access journals.
Harvard University recently adopted a policy where all of its faculty are permitted and encouraged to make their research available as open access. The U.S. National Institutes of Health has an open access policy requiring all research conducted with public funding to make its results open access, at least after a short interval of exclusivity.