Open Access (OA) publications are free to read and free to re-use.
WHO PAYS FOR OPEN ACCESS?
The Open Access model shifts the costs of publishing from readers to authors.
Green vs. Gold
Green OApublishing refers to the self-archiving of published or pre-publication works for free public use. Authors provide access to preprints or post-prints (with publisher permission) in an institutional or disciplinary archive such as eCommons@Cornell
Gold OA publishing refers to works published in an open access journal and accessed via the journal or publisher's website. Examples of Gold OA include PLOS (Public Library of Science) and BioMed Central.
More on OA
While OA is a newer form of scholarly publishing, many OA journals comply with well-established peer-review processes and maintain high publishing standards.