The basewiki is a standard set of wiki pages that are included by default in all wikis that ikiwiki builds, unless the wiki overrides them with its own versions.
It currently includes these pages:
As well as a few other files, like [[favicon.ico]], [[local.css]], [[style.css]], and some icons.
Note that an important property of the basewiki is that it should be
self-contained. That means that the pages listed above cannot link
to pages outside the basewiki. Ikiwiki's test suite checks that the
basewiki is self-contained, and from time to time links have to be
removed (or replaced with
iki [[shortcuts]]) to keep this invariant.