Warhammer 40k - Lexicanum:What links here
What links here is a Special pages tool from the category Page tools. The What links here tool is used to see a list of the pages that link to (or redirect to, or transclude) the current page. These are sometimes also referred to as backlinks. What links here is limited to showing actual backlinks. Pages which contain the title being searched for, but where the title has not been linked (see above), are excluded from the results.
What links here on an article page
The What links here tool can be accessed from the Tools tab at the left side of the screen.
Clicking on this link on an article page shows all other pages that link to the article page in question. You can refine the results by activating a number of filters here such as hiding links, redirects, or transclusions.
What links here from the Special pages overview
The What links here tool can also be accessed via the Special pages tools overview, subsection Page tools.
Since you have not directly accessed the What links here tool from a specific article page you now have to enter the actual article page name you want to use the tool for.
Here you also have the option to specify the Namespace in which the article page name should be searched.
The tool can also be accessed directly by clicking here.
The What links here tool shows all other pages linking to a specific page. This can help to find other pages that are associated with a given page but to which there are no direct links in the article itself. One specific application is when articles have to be renamed, moved, merged, deleted etc. In such cases the original links to the page that has to be changed have to be corrected because otherwise the links might be broken or for example create unwanted Double redirects. The What links here tool helps to track all the links that have to be fixed.
More on the What links here Wikimedia tool can be found here.