Actions are tools that work on a page or the whole wiki, but unlike macros do not add to the page content when viewing a page, but work on that page content. They either produce some output based on page contents (navigational actions like searching) or implement functions that are not related to viewing a page (like deleting or renaming a page).
There is a set of system-defined actions, which includes page editing; you can extend the set of known actions by your own ones. See HelpForDevelopers for more on that.
The following actions are added to the list of user-defined extension actions at the bottom of each page. This happens to any mixed-case extension, for other actions (all lower-case) see the list further down this page. Some of these action might not be available for your wiki site.
DeletePage: Delete a page, after you confirmed it; deletion means a final backup copy is created and only then the page is deleted, i.e. you can revive the page later on (as long as the backups are not physically deleted).
LikePages: list pages whose title starts or ends with the same WikiWord as the current page title.
AttachFile: attach files to a page, see /AttachFile for more details.
LocalSiteMap: show nearby links of the current page, i.e. list all referred-to pages, and in turn their references, to a certain limited depth.
SpellCheck: call the spell checker for the current page; see HelpOnSpellCheck for more.
The following is a list of internal actions that are used to implement the various icons and links at the top and bottom of pages, or supplement certain macros.
inlinesearch: this implements the inline search for the form fields at the bottom of each page (note that this uses POST requests, so you won't normally see this action in URLs). 0.11
highlight: highlight the search word when you click on a link in a search result list.
diff: display differences between page revisions.
info: show meta-data on a page.
recall: display an older revision of a page.
show: display a page (the default action).
refresh: refresh the cached version of a page (currently only used on XSLT-formatted pages).
print: show the print-view of a page, which omits the navigational items from the display view.
edit: edit this page.
savepage: save this page (do not ever use this manually).