Administrators of a wiki-space can restrict access to individual pages in addition to the global permissions set for a wiki-space. Similar to public pages, access restricted pages can be linked in the text. Unauthorized wiki users cannot view the page content, but can request access from the responsible administrator.
In order for individual persons / groups of persons to be able to act in a wiki-space (e.g. edit pages etc.), they must first be given "global" access rights! The subsequently set page restrictions dominate the global permissions.