TWiki is a Web-based
collaboration/
knowledge-base system, a variation on the
Wiki (or
WikiWiki) theme. To the basic Wiki concept it adds user
authentication, page
revision control, and several other features. It is available under the
GPL from
http://twiki.org/.
The original Wiki system, created by Ward Cunningham, has no hard security whatsoever. It has no idea of user accounts, authorization, backups, or the like; any visitor can change anything, irrevocably. From a technical standpoint, it is anarchy; from a social standpoint, its users find that peer pressure, interest, and other factors dissuade people from doing damage ... almost all of the time.
TWiki is an attempt to fit the creative anarchy of the Wiki model to environments where a certain degree of hard security is necessary, generally because gratuitous data loss is unacceptable. Mandatory user accounts make it possible to identify the author of a change. RCS-based versioning and rollback ensure that accidental or malicious deletions do not actually destroy useful information.
One could say that TWiki lies between Wiki and Everything2 in feature-space. Like e2, it has individual accountability of some sort built into the system, and users are prevented from doing permanent damage to other users' work. However, it does not separate users' contributions to a node into writeups owned by the individual users. Neither does it have voting, privileged user groups such as editors, or other implementations of democratic or oligarchic politics.
As it happens, I'm in the process of setting up an experimental TWiki for my employer. Expect more details here if it catches on with the users.
Follow-up, June 2001: We've pretty much decided that TWiki is too complex for our use. Paring it down to what we need would be more work than just coming up with our own Wiki clone, so I'm working on one now.