GNU Free Documentation License

GNU Free Documentation License

The GFDL logo
Author	Free Software Foundation
Latest version	1.3
Publisher	Free Software Foundation, Inc.
Published	November 3, 2008 (current version)
SPDX identifier	GFDL-1.3-or-later GFDL-1.3-only GFDL-1.2-or-later GFDL-1.2-only GFDL-1.1-or-later GFDL-1.1-only (see list for more)
Debian FSG compatible	Yes, with no invariant sections (see below)
GPL compatible	No
Copyleft	Yes
Website	www.gnu.org/licenses/fdl-1.3.html

The GNU Free Documentation License (GNU FDL or GFDL) is a copyleft license for free documentation, designed by the Free Software Foundation (FSF) for the GNU Project. It is similar to the GNU General Public License, giving readers the rights to copy, redistribute, and modify (except for "invariant sections") a work and requires all copies and derivatives to be available under the same license. Copies may also be sold commercially, but, if produced in larger quantities (greater than 100), the original document or source code must be made available to the work's recipient.

The GFDL was designed for manuals, textbooks, other reference and instructional materials, and documentation which often accompanies GNU software. However, it can be used for any text-based work, regardless of subject matter. For example, the free online encyclopedia Wikipedia uses the GFDL^[1] (coupled with the Creative Commons Attribution Share-Alike License) for much of its text, excluding text that was imported from other sources after the 2009 licensing update that is only available under the Creative Commons license.^{[2][circular reference][3][4]}