Review Summary (See also "Comments by Users", below): I see many things to like in this wiki. It stores all past revisions, it has password protection (on the entire site), email notification (by subweb), stores each topic in a separate file (which means an external search engine could provide improved search capabilities with resolution to the topic level), and does not require the use of a database (which makes it less difficult for a newbie to set up). The fact that I can hide text by enclosing it in angle brackets is an advantage to me while I continue to use AskSam for my personal backup.
The screens look more cluttered than those of some other wikis I've seen, which may make using the wiki more daunting for the casual reader / editor. (I am fairly certain there is a way to fix the cluttered screen by changing a template for the screen. The approach of using icons for many of the options, like MoinMoin does, could provide the cleaner interface I'd like to have.) The built-in search facilities are better than some other wikis, but not all that I would like to have. People have experimented with modifying TWiki to use a database, an improvement which might be needed for large WikiSites.
I would like to have password protection and email notification of individual pages or groups of pages. The fact that HTML is allowed worries me, and may be a reason to have password protection on all pages.
All in all, this may be the first wiki I attempt to install, meets many of my needs, and will be my standard for comparison at this time.
Review Quality: First draft. I'm now going to modify some other pages (about searching and databases), but I feel comfortable with this review. There are some open questions. If I install TWiki, I'll learn the answers to those soon enough. I may end up writing to PeterTheony? (or JimWeirrich? because I've corresponded with him previously).
Installation Difficulty: There is an installation tool (I haven't found it yet - I've seen references to it.) There are several pages of installation instructions, including one dealing with the special problems of installing a TWiki on a server where you do not have root privileges. Those instructions are probably helpful for installing any wiki under those circumstances. See http://twiki.sourceforge.net/cgi-bin/view/Codev/SourceForgeHowTo.
Name / cost / limits / URL: None known, but I would see if SourceForge would be willing to host my wiki if it was related to open source (or free) software. They host several wikis using TWiki. I don't know if they have a policy of only hosting TWiki wikis.
Editing Contention Resolution: Yes. When you start an edit, others are locked out until you complete your edit, release the lock, or a timeout occurs (??).
Search capabilities: Words, phrases and regular expressions in titles and body text. No boolean (except via addon), or within x.
Email notification: Yes, by web, not topic (page) or groups of topics. See discussion of multiple webs under "Extra Features".
Diffs: Yes. Added lines prefixed by >, deleted lines prefixed by <. Display compares current version with all previous versions, with comparison to most recent version at top. (uses rdiff?)
Embedded HTML (risky): Yes, at least up to HTML 3.2. Have not seen any reference to the ability to disable or otherwise mitigate the hazards.
Password protection? Passwords can be used to limit editing ability by WikiSite; access control is used to limit users' ability to edit individual topics or webs (although SoftSecurity is preferred).
Delete Pages? Possible in a more recent version.
Revision Snapshots? Every revision (version) is saved. (My guess is that they are saved as a delta. (An administrator can selectively remove revisions.)
Rollback: Yes, not sure of procedure.
Working Well with Others
Static or dynamic web pages:
Indexed by search engines? Can be indexed, e.g. Google indexes TWiki.org (aka twiki.sourceforge.net)
InterWiki Links? Yes. Does not currently use the MeatBall Wiki InterMap database, and requires the InterwikiPlugin?. "Use in your topics the *Externalweb:topic* syntax to link pages in other wikis/sites." ... "All *Externalweb* aliases are kept and managed through the InterWikis? topic.")
Import / Export Features: No specific reference found, the fact that topics are stored one per file in "plain text" files can help.
Translators to/from other Wikis? No specific reference found.
Extra Features: Yes. TWiki has an active community of developers developing some interesting stuff, including:
TWiki makes it easy to create and support multiple webs (sites) on the same server as "subwebs" to a main web. On the TWiki web at SourceForge, there are subwebs named Main, Codev (code development), TWiki, Support (and others). Topics in a different subweb must be linked with a <MainWeb?>.<SubWebTopic?> syntax. Email notification is by subweb. Users log in to the whole site, but if necessary access can be restricted on a subweb or page basis (though using this is discouraged in favour of SoftSecurity). See http://twiki.sourceforge.net/cgi-bin/view/Codev/ScriptToCreateNewWeb.
I've installed and used both the OriginalWiki and Twiki on a low-end web-hosting account (FreeBSD server). While I like many of Twiki's features, I found myself wanting to edit the default templates to reduce the complexity of the UI. I've also spent a lot of time hassling with RCS (the RevisionControlSystem, which Twiki uses to store its revisions; most of the problems have been related to incorrect permissions or the wrong user locking an RCS file. These would be less of a problem if I had root-access to my web-server). Installing the OriginalWiki, OTOH, was a snap and it works. Twiki's great for the corporate environment but I wouldn't recommend it for a non-technical person (either to use or especially to install.) -- MarkShepard?
I am a member of two different groups of adults with moderately good Internet connectivity, and varying computer skills. I'm looking at one form of Wiki or another to try to enhance inter group communication. Playing with a Twiki set up SourceForge, I think the various features will be overwhelming to the point of discouraging (T)wiki use for many group members. Plus I can't find a free TwikiFarm? that fits with either groups' purpose. -- DaveChristenson [I don't quite understand "Playing with a Twiki set up SourceForge" - can you make it clearer?]