Open Access is the unencumbered online access to scholarly research that is free from most copyright and licensing restrictions. This means free access for anyone to read, download, copy, distribute, print, and display.
Read the Open Access Overview by Peter Suber, Director of the Harvard Open Access Project, for an introduction to open access with a focus on publishing in peer-reviewed research articles. View a video of Peter Suber answering the question What is Open Access.
HowOpenIsIt? is a guide from PLoS, SPARC and OASPA, designed to clarify the definitions of open access.
Often, Open Access is primarily --if not exclusively-- defined as a "free" model of publishing. At the very least, this description is incomplete; at worst, it is inaccurate and misleading. "Free" of what? And "free" to whom?
OA distinguishes between two types of freedom: gratis vs. libre.
The gratis vs. libre dichotomy is far from perfect and these definitions don't capture the full complexity of the issue. If you have questions about which "free" you're dealing with or want more information about these and other varieties of "free," contact your liaison librarian or email Jesse Akman (email@example.com) or Betty Garrison (firstname.lastname@example.org).
There are numerous schemata for classifying OA publishing, many of which use or modify the Rights Metadata for Open Archiving (RoMEO) color-coded vocabulary. While this list is not exhaustive and there is a degree of variation to each color's use, common colors include:
Gold OA - Peer-reviewed journals; publisher makes all articles and other content available for free immediately (no embargo); sustained by "Article Processing Charges" (APCs).
Diamond/Platinum OA - Names generally used interchangeably; same qualities as Gold OA, but no charges to authors; without subscription fees or APCs, reliant on alternative funding sources (e.g., advertisements, sponsorships, grants, philanthropy, etc.).
Green OA - Publisher allows permits author self-archiving of pre- and post-print manuscripts (e.g., depositing copy in an institutional repository, posting to a personal website, etc.). Publishing is gratis for authors (i.e., no APCs); however, other charges may be assessed (e.g., licensing for any publisher-authored content in the final manuscript).
Yellow OA - Same as Green, but only allows for depositing pre-print manuscripts
Blue OA - Same as Green, but only allows for depositing post-print manuscripts
Gray OA - OA journals with no peer-review process.
Black OA - Various means and practices for the unauthorized distribution of copyrighted scholarship. Includes formal "shadow libraries" (e.g., SciHub, Libgen, Academic Torrents), as well as informal methods (e.g., soliciting articles with #ICanHazPDF) and analog distribution (e.g., printing a copy for a colleague). Legality and permissibility of these practices varies widely.
There is no "right" color to choose. What OA model is best for you depends on your needs and context. Talk with your liaison librarian or email Jesse Akman (email@example.com) or Betty Garrison (firstname.lastname@example.org) for more information.