The goal of Wikipedia is to create an information source in an encyclopedia format that is freely available. The license we use grants free access to our content in the same sense as free software is licensed freely. That is to say, Wikipedia content can be copied, modified, and redistributed so long as the new version grants the same freedoms to others and acknowledges Wikipedia as the source. Wikipedia articles therefore will remain free forever and can be used by anybody subject to certain restrictions, most of which serve to ensure that freedom.
To fulfill the above goals, the text contained in Wikipedia is licensed to the public under the GNU Free Documentation License (GFDL). The full text of this license is at Wikipedia:Text of the GNU Free Documentation License.
Permission is granted to copy, distribute and/or modify the text of all Wikipedia materials under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts.
The text of the GFDL is the only legally binding document; what follows is our interpretation of the GFDL: the rights and obligations of users and contributors.
IMPORTANT: If you want to use content from Wikipedia, first read the Users' rights and obligations section. You should then read the GNU Free Documentation License.
Users' rights and obligations
If you want to use Wikipedia materials in your own books/articles/web sites or other publications, you can do so, but you have to follow the GFDL, which entails the following:
your materials in turn have to be licensed under GFDL,
you must acknowledge the authorship of the article (section 4B), and
you must provide access to the "transparent copy" of the material (section 4J). (The "transparent copy" of a Wikipedia article is its wiki text.)
If you are simply duplicating the Wikipedia article, the latter two obligations can be fulfilled by providing a conspicuous direct link back to the Wikipedia article hosted on this website.
If you are simply duplicating the Wikipedia article, the latter two obligations can be fulfilled by providing a conspicuous direct link back to the Wikipedia article hosted on this website.