From a page move: This is a redirect from a page that has been moved (renamed). This page was kept as a redirect to avoid breaking links, both internal and external, that may have been made to the old page name.
From incomplete disambiguation: This is a redirect from an incomplete disambiguation, a page name that has been disambiguated and is still too ambiguous to be the title of an article or other project page. Such titles should redirect to an appropriate disambiguation page (or section of it), or to a more complete disambiguation.
To a section: This is a redirect from a topic that does not have its own page to a section of a page on the subject.
When appropriate, protection levels are automatically sensed, described and categorized.