Definitions Diamond, Gold, Green and Hybrid OA
Diamond/Platinum OA: Publish for free in a journal where all the papers are made openly accessible at the time of publication, without any embargo period being required (immediate OA).
Gold OA: Pay an article processing charge (APC) in a journal where all the papers are made openly accessible at the time of publication, without any embargo period (immediate OA).
Green OA: Publish in a subscription-based journal (non-OA) and self-archive the peer-reviewed, accepted version in the institutional repository (self-archiving), possibly with an embargo period (delayed OA). Self-archiving includes also open scholarly articles, books/book chapters and PhD theses.
Hybrid OA: Pay an extra article processing charge (APC) to make your article openly accessible in a subscription-based journal (immediate OA).
Read more about OA definitions (see the sidebar of the webpage)