An open access publication is a publication that provides immediately free online access to all users worldwide. There are many web sites (directories) which list open access journal collections and individual journals. Some of these directories like BioMedCentral and Public Library of Science have very strict peer review processes.
Here is a more formal definition of open access publishing:
"Definition of Open Access Publication
An Open Access Publication is one that meets the following two conditions:
The author(s) and copyright holder(s) grant(s) to all users a free, irrevocable, worldwide, perpetual right of access to, and a license to copy, use, distribute, transmit and display the work publicly and to make and distribute derivative works, in any digital medium for any responsible purpose, subject to proper attribution of authorship as well as the right to make small numbers of printed copies for their personal use.
A complete version of the work and all supplemental materials, including a copy of the permission as stated above, in a suitable standard electronic format is deposited immediately upon initial publication in at least one online repository that is supported by an academic institution, scholarly society, government agency, or other well-established organization that seeks to enable open access, unrestricted distribution, interoperability, and long-term archiving (for the biomedical sciences, PubMed Central is such a repository).
1. Open access is a property of individual works, not necessarily journals or publishers.
2. Community standards, rather than
copyright law, will continue to provide
the mechanism for enforcement of proper attribution and responsible use of the published work, as they do now."
Bethesda Statement on Open Access Publishing
For more about Open Access Publications consult: