The GNU General Public License (short: GNU GPL or simply GPL) is a very popular Free Software License originally written by Richard Stallman for the GNU project and now kept and developed by the Free Software Foundation.
Free in the context of this license means the freedom of the user of the software. Basically, the license gives the right to do anything with the software - except making it unfree somehow. Though code licensed under GPL cannot be distributed in proprietary programs.
The MoinMoin code is licensed under the GPL v2 or (at the user's option) any later version (except some 3rd party modules we use that are licensed under other Free Software licenses compatible with the GPL).
Consequences of this are, for example:
- No vendor lock-in.
- Encouragement and beneficiary of global collaboration.
- Verification from large community and deployment.
Note: We also use some code that is licensed under other, but compatible licenses.