-Ikiwiki requires [[MarkDown]] be installed, and also uses the following
-perl modules if available: `CGI::Session` `CGI::FormBuilder` (version
-3.02.02 or newer) `HTML::Template` `Mail::SendMail` `Time::Duration`
-`Date::Parse` (libtimedate-perl), `HTML::Scrubber`, `RPC::XML`,
-`XML::Simple`
+Ikiwiki is a perl program, and needs a recent version of perl such as
+5.8.8. (5.8.0 has been reported not to work).
+
+Ikiwiki requires [[MarkDown]] and the `URI` and `HTML::Parser` perl
+modules be installed, and also uses the following perl modules if
+available:
+`CGI::Session` `CGI::FormBuilder` (version 3.02.02 or newer)
+`HTML::Template` `Mail::Sendmail` `Time::Duration` `Date::Parse`,
+`HTML::Scrubber`, `RPC::XML`, `XML::Simple`, `XML::Feed`.
+
+The [[tla]] support also needs the `MailTools` perl module.
+
+Various [[plugins]] use other libraries and utlities; see their individual
+documentation for details.
+
+If you're installing MarkDown by hand, note that it should be installed as
+`Markdown.pm` somewhere in perl's module search path, or alternately as
+`/usr/bin/markdown`. Ikiwiki will find it under either name.