+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. Most of ikiwiki's features are actually provided by plugins.
+Ikiwiki's backend RCS support is also pluggable, so support for new
+revision control systems can be added to ikiwiki.
+
+The standard language for ikiwiki plugins is perl, but ikiwiki also supports
+[[plugins/write/external]] plugins: Standalone programs that can be written in
+any language and communicate with ikiwiki using XML RPC.
+
+## [[todo/utf8]]
+
+After rather a lot of fiddling, we think that ikiwiki correctly and fully
+supports utf8 everywhere.
+
+## Other features
+
+The above are the core design goals and features of ikiwiki, but on that
+foundation a lot of other important features are added. Here is an
+incomplete list of some of them.
+
+### [[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 and Atom feeds.
+
+### [[SubPages|SubPage]]
+
+Arbitrarily deep hierarchies of pages with fairly simple and useful
+[[SubPage/LinkingRules]]
+
+### [[BackLinks]]
+
+Automatically included on pages. Rather faster than eg MoinMoin and
+always there to help with navigation.
+
+### Smart merging and conflict resolution in your web browser
+
+Since it uses a real RCS, 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 commit conflict 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.
+
+### [[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 edit
+pages.
+
+User registration can be done using a web form, or ikiwiki can be
+configured to accept users authenticated with OpenID, or HTTP basic
+authentication, or other methods implemented via plugins.
+
+### 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.
+
+### Edit controls
+
+Wiki admins can [[lock_pages|page_locking]] so that only other admins can
+edit them. Or a wiki can be set up to allow anyone to edit Discussion
+pages, but only registered users to edit other pages. These are just two
+possibilities, since page edit controls can be changed via plugins.
+
+### [[PageHistory]]
+
+Well, sorta. Rather than implementing YA history browser, it can link to
+[[ViewVC]] or the like to browse the history of a wiki page.
+
+### 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.
+
+### [[w3mmode]]
+
+Can be set up so that w3m can be used to browse a wiki and edit pages
+without using a web server.