The original WikiWikiWeb_ was established in 1995 by Ward Cunningham, who invented and named the Wiki concept and produced the first implementation of a WikiWiki_ server. Ward's server is still online at http://www.c2.com/cgi/wiki. Visit that server for additional information. Or read a book Ward (and Bo Leuf) wrote on the concept: The Wiki Way: Quick collaboration on the Web, Addison-Wesley, ISBN-020171499X. Some people maintain that only Ward's wiki should be called "Wiki" (upper case) or the "WikiWikiWeb_".
Note that wiki is sometimes (erroneously?) spelled wikki.