"Wikipedia is a free, Web-based, collaborative, multilingual encyclopedia project supported by the nonprofit Wikimedia Foundation."

Since its beginnings in 2001, Wikipedia has amassed an archive of 18 million entries in about 279 languages and is one of the 10 most popular Web sites on the Internet.

The power of Wikipedia is encapsulated in some basic facts about that self-defining article, "Wikipedia" — a founding document of sorts. The article, as of this writing, runs more than 7,100 words (with links to more detailed subsections), with more than 210 footnotes and a dozen graphical elements, including a video clip, photographs, a cartoon, newspaper clippings and charts and graphs. Like every entry in the online encyclopedia, it began with someone using the editing tool on the site to create an article — typically an article begins as a "stub," a first stab at defining a topic. Someone else typically expands it, while another contributor may shrink it again; some edit for style, others for typos.

Multiply that experience by over three million (for the number of English language articles) and you begin to understand the magnitude of information that has been collected on Wikipedia. In addition to the articles themselves, and the associated art work, the servers that host Wikipedia store detailed records of each and every change to an article (excluding some vandalism that is purged forever) and complementary pages for discussing editing issues related to each article. (To examine in detail how an article has been edited click on the History tab at the top of an article — by choosing one of the entries you will find colored texts to show what material was added, what material was changed; to follow the debates, click on the Discussion tab.)

Following years of spectacular growth, Wikipedia faced in 2010 practical questions of how to deal with the problems of success and acceptance.

As growth slowed in the United States and Europe, the group's organizers have held strategy sessions to spur growth in less developed countries, as well as among women, older people and less technically savvy. At the same, there have been efforts to work with experts to include their contributions on the site — a notion that would have been heretical not too long ago.