Open Access (OA) literature is online, free to read, and free of most copyright and licensing restrictions. --Peter Suber
OA Explained (8-min video)
Going for Gold and Green Pastures: OA Explained (slideshare)
The Right to Research Coalition (Access to Research is a Student Right)
OA isn't an attempt to bypass peer review; restrict academic freedom; relax the rules against plagiarism; or violate copyright.
OA isn't an attempt to deny the reality of costs. The question is not whether research literature can be made costless, but whether there are better ways to pay the bills than charging readers and creating access barriers
OA is not a means to reduce authors' rights over their work. If fact, OA requires an author to exercise more rights than under traditional publishing contracts.
OA is not about punishing or undermining conventional publishers (it's about advancing the interests of research, researchers and research institutions).
OA isn't primarily about bringing access to lay readers. The OA movement focuses on bringing access to professional researchers whose careers depend on access.
Increased discoverability of articles by potential readers worldwide because: (a) the research is found more easily via Internet searches; and (b) the research is available to all potential readers without a prior subscription or payment; earlier access to OA research versus traditional publishing channels that have longer lag times between acceptance and dissemination. A 2014 PLoS ONE study estimates that 24% of scholarly information is freely available online.
Increased downloads and readership of OA articles because the full text is available online for free
Increased citations of your articles (though there are several contradictory studies in this area)
See SPARC's Why Open Access? for more information