Editing Help:Link (section)

=== Checking links ===

Make sure to use the "Show preview" button (between "'''Save page'''" and "Show changes" at the bottom of the page) to check that all of your internal links resolve.  If you see any redlinks, either the article does not exist (if you think the article should exist, leave the link where it is and it may get created) or the article name has been misspelled.  This can be the result of mixing up the case (e.g. "Space marine" is different from "Space Marine"), plural/singular (articles should generally have singular titles, categories should generally be plural -- if you need to spell out a term in plural while the article title is singular, use a piped link or tack on the -s or -es as in the "Troll(s)" example above), or a typo.