Open Access stands for toll-free online access to scientific and scholarly literature with the aim of ensuring maximum dissemination and rapid availability of research.
The Budapest Open Access Initiative defines Open Access: "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."
Peter Suber, independant policy strategist for open access to research, points out that Open Access literature is digital, online, free of charge, and free of most copyright and licensing restrictions. Yet it is compatible with copyright, peer review, revenue, prestige and quality. Read Peter Suber's Open Access Overview or this brief introduction for more information.