What is a Wiki? A wiki is an open, collaborative website whose content is built and maintained in large measure by its visitors. A complete definition is available at the Webopedia. The practical upshot, though, is that you -- the casual visitor -- are allowed and encouraged to correct, revise, and add to the content you see here.
Why in the world would you allow a casual visitor to change your content? Wiki projects such as this one are based on the premise that the group is smarter than the individual. Therefore the collective work of both experts and non-experts, given moderate controls, will produce a more accurate and complete work than that of an individual alone. You can read more about group wisdom in [http://www.amazon.com/exec/obidos/tg/detail/-/0385503865/ref=wl_it_dp/104-6227076-6203105?_encoding=UTF8