This is a structured response letter for enquirers wanting to re-use Wikipedia content in a commercial setting

Thankyou for your enquiry regarding the commercial use of content from Wikipedia.

Wikipedia is an online open-content collaborative encyclopedia; that is, a voluntary association of individuals and groups who are developing a common resource of human knowledge. The structure of the project allows anyone with an Internet connection and World Wide Web browser to alter its content. Please be advised that nothing found on Wikipedia has necessarily been reviewed by professionals with the expertise required to provide you with complete, accurate or reliable information.

That is not to say that you will not find valuable and accurate information in Wikipedia; much of the time you will. However, Wikipedia cannot guarantee the validity of the information. The content of any given article may recently have been changed, vandalized or altered by someone whose opinion does not correspond with the state of knowledge in the relevant fields.

Wikipedia contributions are voluntarily given by editors under the GNU Free Documentation License (GFDL) [1], which applies the legal principle known as copyleft; a way of using the copyright process to prevent information being controlled by any one person to ensure it remains freely accessible forever.

Some content, however, may be subject to different rights in each country due to local variations in copyright law, and http://en.wikipedia.org/wiki/Wikipedia:Copyright should be referred to about this before re-using content, especially images. For example, if we include an image under fair use, you must ensure that your use of that article also qualifies for fair use.

Wikipedia does use some text under licenses that are compatible with the GFDL but may require additional terms that we do not require for original Wikipedia text (such as including Invariant Sections, Front-Cover Texts, or Back-Cover Texts). When using these materials, you have to include those invariant sections verbatim.

All of the information in Wikipedia is free for anyone to copy, modify for their own purposes, and redistribute or use as they see fit, as long as the new version grants the same freedoms to others and acknowledges the authors of the Wikipedia article used. Wikipedia is open to a large contributor base so it is less susceptible to retaining bias, is very hard for any group to censor, and is far more responsive to new information, especially information not widely known in the West. This also means it is more easily vandalized or susceptible to unchecked information later needing removal. As such you should always confirm any information you use with other sources if you are in doubt about any content and, ideally, a citation [2] should normally include the full date and time of the article revision you are using, because the page may well change radically between when you view (copy) it and when somebody else following your reference views it. This can be found by clicking the Page history link at the left or top of the page, and looking at the time of the topmost revision (times are in Coordinated Universal Time, or UTC, unless you have logged in and entered an offset in your preferences). You can also find the date and time of last revision at the bottom of the page.

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. For a derivative version - by changing, deleting or adding content - this 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 any of a number of formats available from us, including the wiki text, the html web pages, xml feed, etc.)

For web-based usage, you may be able to partially fulfill the latter two obligations by providing a conspicuous direct link back to the Wikipedia article hosted on our website. You also need to provide access to a transparent copy of the new text. However, please note that the Wikimedia Foundation makes no guarantee to retain authorship information and a transparent copy of articles. Therefore, you are encouraged to provide this authorship information and a transparent copy with your derived works.

In general you are not required to cite any particular author or authors for a Wikipedia article as Wikipedia is collaboratively written. However, if you do need to find the list of authors of a particular article, you can check the Page history. Your citation should, however, list both the article title and "[from] Wikipedia, The Free Encyclopedia" in a location and font clearly identifiable as related to the text in use. You may not imply that your usage is sponsored or promoted by the Wikimedia Foundation or Wikimedia UK.

Should you have any further queries, feel free to contact me.

Alison Wheeler
Chair, Wikimedia UK
e: [email protected]

[1] http://en.wikipedia.org/wiki/GNU_Free_Documentation_License
[2] http://en.wikipedia.org/wiki/Wikipedia:Citing_Wikipedia