One criticism levied at open access is that it is not actually free. That is certainly true, and in fact, open access advocates make no claim that open approach is costless. However, the costs of supporting open access publishing are not paid by those needing access to research. And open access models that do not attempt to support for-profit businesses also appear to cost less, overall.
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.
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.
Examples: BioMed Central, PloS
University of Minnesota is an institutional member of both BioMed Central and Public Library of Science.
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.
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.