The following quotes are all from Wikipedia:About.
"Wikipedia (IPA: /ˌwikiˈpiːdi.ə/ or /ˌwɪkiˈpiːdi.ə/) is a multilingual, web-based, free content encyclopedia project. Wikipedia is written collaboratively by volunteers from all around the world. With rare exceptions, its articles can be edited by anyone with access to the Internet, simply by clicking the edit this page link. The name Wikipedia is a portmanteau of the words wiki (a type of collaborative website) and encyclopedia. Since its creation in 2001, Wikipedia has grown rapidly into one of the largest reference Web sites."
"Because Wikipedia is a going work to which, in principle, anybody can contribute, it differs from a paper-based reference source in important ways. ... However, unlike a paper reference source, Wikipedia is continually updated, with the creation or updating of articles on topical events within minutes or hours, rather than months or years for printed encyclopedias."
"Tens of thousands of regular editors — from expert scholars to casual readers — can edit Wikipedia, an openness that encourages inclusion of a tremendous amount of content.
Several mechanisms are in place to help Wikipedia members carry out the important work of crafting a high-quality resource while maintaining civility. Editors can watch pages and techies can write editing programs to keep track of or rectify bad edits. Over 1,000 administrators with special powers ensure that behavior conforms to Wikipedia guidelines and policies."
"Many visitors come to this site to acquire knowledge, others to share knowledge. In fact, at this very instant, dozens of articles are being improved, and new articles are also being created. "
"Wikipedia articles are all linked, or cross-referenced. Wherever you see highlighted text like this, it means there is a link to some relevant article or Wikipedia page with further in-depth information elsewhere if you need it."
"As a wiki, articles are never complete. They are continually edited and improved over time, and in general this results in an upward trend of quality, and a growing consensus over a fair and balanced representation of information.
Users should be aware that not all articles are of encyclopedic quality from the start, and may contain false or debatable information. Indeed, many articles start their lives as partisan, and it is after a long process of discussion, debate and argument, that they gradually take on a neutral point of view reached through consensus. Others may for a while become caught up in a heavily unbalanced viewpoint which can take some time — months perhaps — to extricate themselves and regain a better balanced consensus."
"Several studies suggest that the science entries of Wikipedia are of a similar order of accuracy and similar rates of both serious and minor errors to Encyclopedia Britannica, that it provides a good starting point for research, and that articles are in general reasonably sound. However, it does suffer from omissions and inaccuracies and sometimes these can be serious."
"Wikipedia's greatest strengths, weaknesses and differences arise because it is open to anyone, has a large contributor base, and articles are written by consensus according to editorial guidelines and policies. The MediaWiki software which runs Wikipedia retains a history of all edits and changes, thus information added to Wikipedia never 'vanishes', and is never 'lost' or deleted."