Open-access is a copyright issue, not (as many people think) an issue about the presense or absence of peer review or the replacement of hard-copy print publication.

Open-access publishing has three main implications: i) the author retains copyright; ii) the author grants permission to others to access and distribute that material for any non-commercial purpose, provided authorship and copyright are clearly indicated; and iii) the work is made available for free online at one or another sort of stable archiving source.

Note that (iii) does not rule out also making the same work available in hard copy. So for example, an open access journal could be simultaneously published online (with free access) as well as a hard copy print edition (perhaps with some sort of fee to cover the costs of producing and mailing the hard copy).

Also, note that open-access does not have any implications for the decision proceedure for what gets published. Some open-access venues might not have peer review (as indeed many current print journals operated by commercial publishers in our discipline do not), and some -- an excellent example as The Philosophers Imprint -- have very high peer-review standards.

This was purposefully brief, and left many questions unanswered. For more information -- such as the personal benefits authors stand to gain by publishing work in open-access venues, the social-responsibility benefits of open-access publication, and detailed reports about various initiatives -- please click on one of the links to the left.