Ten things you may not know about Wikipedia is a list of insights about Wikipedia specifically targeted at people who have limited or no prior experience with the project (such as journalists, new editors, and new readers). These explanations should not surprise experienced editors but will hopefully help the rest of the world to shape an informed opinion of our work.

If you're waiting for Wikipedia to be bought by your friendly neighborhood Internet giant, don't hold your breath. Wikipedia is a non-commercial website run by the Wikimedia Foundation, a 501(c)(3) non-profit organization based in San Francisco. We are supported by donations and grants, and our mission is to bring free knowledge to everyone.

Wikipedia has taken a cue from the free software community (which includes projects like GNU, Linux and Mozilla Firefox) and has done away with traditional copyright restrictions on our content. Instead, we've adopted what is known as a "free content license" (specifically, a choice between the CC BY-SA and the GFDL): almost all text and composition created by our users is and will always remain free for anyone to copy, modify, and redistribute. We only insist (and our licenses require) that you credit the contributors, state the free license your re-use is under, and that you do not impose new restrictions on the work or on any improvements you make to it. Many of the images, videos, and other media on the site are also under free licenses, or in the public domain. Just check a file's description page to see its licensing terms.

... and about 300 other languages. Granted, only about 100 of those Wikipedia language editions currently have more than 10,000 articles—but that is not because we're not trying. Articles in each language are generally started and developed independently from their equivalents in other languages, although some are direct translations. The Wikimedia Foundation is supported by a growing network of independent chapter organizations, already in over twenty countries, which help us to raise awareness on the local level. In many countries, including the United States, Wikipedia is among the ten most popular websites.

Any piece of information in Wikipedia can be changed. If the change is properly sourced it will remain unless reverted (a talk page discussion can then take place to question the reversal), and contribute to the body of knowledge. If a change is unsourced or merely an editor's opinion, it can be removed. Generally, nothing in Wikipedia is permanently deleted (with some exceptions related to privacy). Wikipedia keeps a complete record of changes to its content. So, if something needs to be restored, that is easily done.  

Wikipedia has a set of policies and quality control processes. Editors can patrol changes as they happen, monitor specific topics of interest, follow a user's track of contributions, tag problematic articles for further review, report vandals, discuss the merits of each article with other users, and much more. What are felt to be our best articles are awarded "featured article" status, and problem pages are nominated for deletion. "WikiProjects" focus on improvements to particular topic areas. Really good articles may go into other media and be distributed to schools through Wikipedia 1.0. We care about getting things right, and we never stop thinking about new ways to do so.

It is in the nature of an open collaboration and work-in-progress like Wikipedia that quality may vary over time, and from article to article. While some articles are of the highest quality of scholarship, others are admittedly complete rubbish. Also, since Wikipedia can be edited by anyone at any time, articles may be prone to errors, including vandalism, so Wikipedia is not a reliable source. So, please do not use Wikipedia to make critical decisions. This encyclopedia is especially useful for improving familiarity with a subject and its jargon, and for learning search terms with which to further explore a subject beyond Wikipedia. Helpful external links are also provided to assist you in learning more.

Wikipedia is part of a growing movement for free knowledge that is beginning to permeate science and education. The Wikimedia Foundation directly operates ten sister projects to the encyclopedia: Wiktionary (a dictionary and thesaurus), Wikisource (a library of source documents), Wikimedia Commons (a media repository of more than forty million images, videos, sound files and other media), Wikibooks (a collection of textbooks and manuals), Wikiversity (an interactive learning resource), Wikinews (a citizen journalism news site), Wikiquote (a collection of quotations), Wikispecies (a directory of all forms of life), Wikidata (a knowledge base) and Wikivoyage (a travel guide). Like Wikipedia itself, all these projects are freely licensed and open to contributions.

Articles in Wikipedia do not include bylines, and contributors are unpaid volunteers. Whether you claim to be a tenured professor, use your real name, prefer to remain pseudonymous, or contribute without registering, your edits and arguments will be judged on their merits. We require that verifiable sources be cited for all significant claims, and we do not permit editors to publicize their personal conclusions when writing articles. All editors must follow a neutral point of view; they must only collect relevant opinions which can be traced to reliable sources.

The Wikimedia Foundation is controlled by its Board of Trustees, which is required according to its Bylaws to have several members chosen from the Wikimedia community. The Board and Wikimedia Foundation staff do not usually take a role in editorial issues, and projects are self-governing and consensus-driven. Wikipedia co-founder Jimmy Wales occasionally acts as a final arbiter on the English Wikipedia. Wikipedia is transparent and self-critical; controversies are debated openly and even documented within Wikipedia itself when they cross a threshold of significance.

We want Wikipedia to be around at least a hundred years from now, if it does not turn into something even more significant. Everything about Wikipedia is engineered towards that end: our content licensing, our organization and governance, our international focus, our fundraising strategy, our use of free software, and our never-ending effort to achieve our vision. We want you to imagine a world in which everyone can freely share in the sum of all knowledge. That is our commitment—and we want your help.

• Wikipedia:Ten things you may not know about images on Wikipedia
• What Wikipedia is not