While "Open Access" has a fairly well-bounded definition, there are a wide variety of approaches to achieving open access, both for individual authors, and at the publication or publisher level.
Many publications have policies that allow authors to post copies of articles on their personal websites, or in institutional or subject repositories, after publication. Many of these policies have limitations: the author can only post the final edited manuscript; the author must wait 6 months (or 12 months) after publication before posting, etc. You can find out more about the policies of various publishers in the SHERPA/RoMEO database.
Authors can also, regardless of publisher policy, negotiate with their publisher to retain some rights to the article, or for the author and the publisher to share many of the rights. (More on negotiating about rights.) Many Universities also have open access policies that help authors maintain their ability to self-archive. (More on the UMN open access policy.)
The University of Minnesota has an institutional repository where authors are welcome to deposit copies of articles for open access - the University Digital Conservancy.
- Delayed Open Access:
Offering free access after a specified period. A journal will make its articles freely available after a period of time, anywhere from 6 months to 2 years. The delayed access helps the publisher preserve the subscription base.
- Short-term Open Access:
Providing free access to articles for a short period after publication, after which they are only available to subscribers.
- Selected Open Access:
Selected articles are freely available, while the rest of the issue requires a subscription to access. Often related to Hybrid Open Access, below.
- Hybrid Open Access:
The author is given the option to pay a publication charge to make his or her article Open Access immediately on publication. Access to articles by authors who choose not to pay (and other content) require a subscription.
- Partial Open Access:
The journal's primary research articles are freely available, but access to other value-added content such as editorials and review articles requires a subscription.
Examples: BioMed Central's Genome Biology
- Total Open Access:
All the articles in the journal are completely and unrestrictedly accessible on the Internet. Article processing fees are usually required to cover the costs of peer-review and online publication and are paid by the author, the author's institution or the author's research grant. Many open access journals offer institutional memberships, where based on the level of membership, article processing fees are either reduced or entirely waived.
With institutional membership, faculty and staff receive discounts on article processing charges for articles that are published in BMC and PLOS journals (15% for BMC, 10% for PLOS). For BioMed Central, the University also receives discounts on other BioMed Central products, like the Faculty of 1000.