These are the six available Creative Commons licenses which are combinations of the four elements above. See "About CC Licenses". In addition, there are two additional designations.
ONLY those highlighted in yellow are permitted by Wikimedia Commons for use in Wikipedia. Wikimedia forbids use of Non-Commercial or No-Derivatives licenses.
Attribution-ShareAlike CC BY-SA
Attribution-NoDerivs CC BY-ND
Attribution-NonCommercial CC BY-NC
Attribution-NonCommercial-ShareAlike CC BY-NC-SA
Attribution-NonCommercial-NoDerivs CC BY-NC-ND
graphics from Creative Commons
CC0 (No Rights Reserved) is a Public Domain Dedication offered by the Creative Commons for creators who opt out of copyright protection (though this opt-out may not apply to every jurisdiction).
Public Domain Mark (No Known Copyright) allows institutions to communicate when a work is no longer under copyright and therefore can be freely used by others.
Wikimedia only permits the use of images with the Most Open licenses on this graphic - the top three aligned with the green bar.
graphic from Creative Commons
The Wikimedia Commons includes freely usable media files. You can contribute files to Wikimedia.
Merced assembly center