"Wiki" is the Hawaiian work for "quick", or so they say at the original
wiki website at http://c2.com/cgi/wiki.  The idea started in 1995 by
Ward Cunningham.
The idea behind wiki is to turn web content users into content providers.
Instead of a few people with special access permissions writing all
the documentation pages, all users get to contribute on an equal basis
in a frantic, uncontrolled, free-for-all.

Everyone is encouraged to contribute content to the wiki.
No specially text formatting language skills are required.
Wiki content looks like plain text.  There are some
simple rules for FormattingWikiPages that are learned in
just a few minutes.