Starting and Running a Wiki Website/Choosing a License

Before you start a wiki, it is essential to choose a suitable license. Once users start contributing to a wiki in which the license is not clearly specified, you may run into a licensing nightmare, having to track the authors of content without proper license.

The licenses proper to a wiki include:
 * FDL. GNU Free Documentation License, used by Mediawiki projects. Beware that this license is incompatible with GNU General Public License. Choosing a GNU GPL for a wiki is unfortunate, as it has been designed for software, not for texts in human language.
 * Creative Commons. One of the Creative Commons licenses
 * Combination of the two
 * PD. Public domain license, the least restrictive license.

According to some interpretations of the law, it may be illegal to ever change the copyright license of a wiki without getting explicit, written consent from everyone who has ever posted on the wiki, unless the copyright license itself has explicit provisions for changing the license.

The public domain license is the only license that lets you change the license later. If you or your users later decide they want some license other than public domain, you might want to check out the license comparisons in Further reading.