A Not So Brief Introduction to Public Access. This is a succinct review of the concept of open access by Peter Suber. It also contains a link to an online book on the subject.
Public Library of Science. PLOS is a nonprofit organization of scientists and physicians committed to making the world's scientific and medical literature a freely available public resource.
Open Access. Wikipedia entry.
Open Access Directory. This is a resource created and maintained by the open access community to provide the facts about open access in practice
Open Access, as defined by the Scholarly Publishing and Academic Resources Coalition (SPARC), is the "free, immediate, availability on the public Internet of those works which scholars give to the world without expectation of payment - permitting any user to read, download, copy, distribute, print, search, or link to the full text of these articles, crawl them for indexing, pass them as data to software, or use them for any other lawful purpose" (Why Open Access?, 2013).
The spread of the concept of open access parallels the rise in use of the Internet and the increasing findability of information. It is meant to be independent of format.