Some of ikiwiki's features:

* [[Subversion]]

  Rather than implement its own system for storing page histories etc,
  ikiwiki simply uses subversion. (It's also possible to [[plugins/write]]
  support for other systems, and ikiwiki also includes support for [[Git]]
  now.)

  Instead of editing pages in a stupid web form, you can use vim and commit
  changes via svn. Or work disconnected using svk and push your changes out
  when you come online.

  ikiwiki can be run from a [[post-commit]] hook to update your wiki
  immediately whenever you commit.

  Note that ikiwiki does not require subversion to function. If you want to
  run a simple wiki without page history, it can do that too.

* [[MarkDown]]

  ikiwiki supports pages using [[MarkDown]] as their markup language. Any
  page with a filename ending in ".mdwn" is converted from markdown to html
  by ikiwiki. Markdown understands text formatted as it would be in an email,
  and is quite smart about converting it to html. The only additional markup
  provided by ikiwiki on top of regular markdown is the [[WikiLink]] and 
  [[PreprocessorDirective]]

  If you prefer to use some other markup language, ikiwiki allows others to
  easily be added by [[plugins]]. For example it also supports traditional
  [[plugins/WikiText]] formatted pages or pages written as pure
  [[plugins/HTML]].

* support for other file types

  ikiwiki also supports files of any other type, including plain text,
  images, etc. These are not converted to wiki pages, they are just copied
  unchanged by ikiwiki as it builds your wiki. So you can check in an image,
  program, or other special file and link to it from your wiki pages.

* [[SubPages|SubPage]]

  Arbitrarily deep hierarchies of pages with fairly simple and useful
  [[SubPage/LinkingRules]]

* [[blogging|blog]]

  You can turn any page in the wiki into a [[blog]]. Pages matching a
  specified [[PageSpec]] will be displayed as a weblog within the blog
  page. And an RSS feed can be generated to follow the blog.

  Ikiwiki's own [[TODO]], [[news]], and [[plugins]] pages are good examples
  of some of the flexible ways that this can be used.

  Ikiwiki can also [[plugin/aggregate]] external blogs, feeding them into
  the wiki. This can be used to create a Planet type site that aggregates
  interesting feeds.

* [[tags]]

  You can tag pages and use these tags in various ways. Tags will show
  up in the ways you'd expect, like at the bottom of pages, in blogs, and
  in rss feeds.

* Fast compiler

  ikiwiki is fast and smart about updating a wiki, it only builds pages
  that have changed (and tracks things like creation of new pages and links
  that can indirectly cause a page to need a rebuild)

* valid html and css

  ikiwiki aims to produce 
  [valid XHTML 1.0](http://validator.w3.org/check?url=referer).
  ikiwiki generates html using [[templates]], and uses css, so you can 
  change the look and layout of all pages in any way you would like.

* [[BackLinks]]

  Automatically included on pages. Rather faster than eg MoinMoin and
  always there to help with navigation.

* [[PageHistory]]

  Well, sorta. Rather than implementing YA history browser, it can link to
  [[ViewCVS]] or the like to browse the history of a wiki page.

* [[RecentChanges]], editing pages in a web browser

  Nearly the definition of a wiki, although perhaps ikiwiki challenges how
  much of that web gunk a wiki really needs. These features are optional
  and can be enabled by enabling [[CGI]].

* User registration

  Can optionally be configured to allow only registered users to post
  pages; online user registration form, etc.

* Discussion pages

  Thanks to subpages, every page can easily and automatically have a
  /Discussion subpage. By default, these links are included in the
  [[templates]] for each page.

* Smart merging and conflict resolution in your web browser

  Since it uses subversion, ikiwiki takes advantage of its smart merging to
  avoid any conflicts when two people edit different parts of the same page
  at the same time. No annoying warnings about other editors, or locking,
  etc, instead the other person's changes will be automatically merged with
  yours when you commit.

  In the rare cases where automatic merging fails due to the same part of a
  page being concurrently edited, regular subversion commit markers are
  shown in the file to resolve the conflict, so if you're already familiar
  with that there's no new commit marker syntax to learn.

* page locking

  Wiki admins can lock pages so that only other admins can edit them.

* Full text search

  ikiwiki can use the [[HyperEstraier]] search engine to add powerful
  full text search capabilities to your wiki.

* Commit mails

  ikiwiki can be configured to send you commit mails with diffs of changes
  to selected pages.

* [[Plugins]]

  Plugins can be used to add additional features to ikiwiki. The interface
  is quite flexible, allowing plugins to implement additional markup
  languages, register [[PreProcessorDirective]]s, hook into [[CGI]] mode,
  and more. Ikiwiki's backend RCS support is also pluggable, so support for
  new revision control systems can be added to ikiwiki. 

* [[todo/utf8]]

  After rather a lot of fiddling, we think that ikiwiki correctly and fully
  supports utf8 everywhere.

* [[w3mmode]]

  Can be set up so that w3m can be used to browse a wiki and edit pages
  without using a web server.

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It also has some [[TODO]] items and [[Bugs]].