What links here is a special page which allows users to check which pages link to any given page on Memory Alpha. There are three ways to access it: directly, by going to Special:WhatLinksHere; via the "What links here" button under "My Tools" in the toolbar; or by way of the "What links here" link under "Page Tools" in the sidebar appearing at the right of most pages.
The what links here listing can be filtered by namespace. You can hide transclusion, links, and/or redirects from a "what links here" results listing. What links here also works for pages that do not exist (yet), making it useful in determining which pages link to a given nonexistent page. In all cases, the result pages are ordered based on how long they have linked to the given page.