Many academic institutions have joined the Budapest Open Access Initiative (BOAI) which defines "open access" as follows:
By "open access" to this literature, we mean its free availability on the public internet, permitting any users to read, download, copy, distribute, print, search, or link to the full texts of these articles, crawl them for indexing, pass them as data to software, or use them for any other lawful purpose, without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself. The only constraint on reproduction and distribution, and the only role for copyright in this domain, should be to give authors control over the integrity of their work and the right to be properly acknowledged and cited.
In addition to benefiting consumers of scholarly information, open access also benefits scholars, increasing the visibility, influence, and potential benefit of their research. It helps redress global inequity of access to scholarship by dismantling cost barriers to research dissemination. And it returns research results more swiftly and readily to the public, who provide much of the funding for scholarly work.