The CC licenses all grant the “baseline rights”, such as the right to distribute the copyrighted work worldwide for non-commercial purposes, and without modification. The details of each of these licenses depends on the version, and comprises a selection out of four conditions:
|Attribution(BY)||Licensees may copy, distribute, display and perform the work and make derivative works based on it only if they give the author or licensor the credits in the manner specified by these.|
|Share-alike(SA)||Licensees may distribute derivative works only under a license identical to the license that governs the original work.|
|Non-commercial (NC)||Licensees may copy, distribute, display, and perform the work and make derivative works based on it only for noncommercial purposes.|
|No Derivative Works (ND)||Licensees may copy, distribute, display and perform only verbatim copies of the work, not derivative works based on it.|
The last two clauses are not free content licenses, according to definitions such as DFSG or the Free Software Foundation’s standards, and cannot be used in contexts that require these freedoms, such as Wikipedia. For software, Creative Commons includes three free licenses created by other institutions: the BSD License, the GNU LGPL, and the GNU GPL.
Mixing and matching these conditions produces sixteen possible combinations, of which eleven are valid Creative Commons licenses and five are not. Of the five invalid combinations, four include both the “nd” and “sa” clauses, which are mutually exclusive; and one includes none of the clauses. Of the eleven valid combinations, the five that lack the “by” clause have been retired because 98% of licensors requested attribution, though they do remain available for reference on the website. This leaves six regularly used licenses:
|Attribution + NoDerivatives||BY-ND|
|Attribution + ShareAlike||BY-SA|
|Attribution + Noncommercial||BY-NC|
|Attribution + Noncommercial + NoDerivatives||BY-NC-ND|
|Attribution + Noncommercial + ShareAlike||BY-NC-SA|
For example, the Creative Commons Attribution (BY) license allows one to share and remix (create derivative works), even for commercial use, so long as attribution is given.