Open access (OA) means that full-text research papers are available online as soon as they are published, free of charge and most copyright restrictions on access or use. For a concise introduction to key OA concepts and issues, read Open Access Overview by Peter Suber, one of the leading authorities on open access movement.
Gratis Open Access refers to works that are available free of charge, while some copyright and licensing restrictions may still apply.
Libre Open Access refers to works that are available free of charge and free of most copyright and licensing restrictions.
Reader rights. Free readership rights to all articles immediately upon publication
Reuse rights. Generous reuse & remixing rights (e.g., CC BY license)
Copyrights. Author holds copyright with no restrictions
Author posting rights. Author may post any version to any repository or website with no delay
(Adapted from SPARC's HowOpenIsIt? CC-BY)