Let's say you are writing about Jack Jackson, who trades options. Both Jack and options are relevant topics. Trouble is, Jack’s real name is Wilbur Shandlin (Jack) Jackson, and that’s what his page is called. Oh, and the page for “options” is actually “option”. If you're putting in topic links without changing your text, you might do this:
One of the company’s noted newcomers is [[Jack Jackson]], who has been trading [[options]] for years. [[Jackson’s]] track record was less than stellar in 2007.
All of the above links, however, will not find their existing article pages because the wiki requires an exact match between the name of the page and the topic link. The links will appear red, and anyone who clicks on them will be asked if they want to create the new page.
The difficult (and wrong) way to fix this problem would be to create redirection pages (that use #REDIRECT) for all the differently-worded topics. This fills up the wiki with a lot of unnecessary redirections, impacting database performance as the months and years pass. It also wastes your time as you have to go back and create several new pages for every article you add, when there's already a perfectly good page just waiting to be linked.
By the way, #REDIRECT is actually a good idea for “Jack Jackson” if everybody knows him by that name, but there's a good chance that the creator of Jack's article has already done that.
To link "option" when your article's word is "options", simply put the topic link around the part of the word that has the name, like this:
The whole word will light up as linked, but now it will take the reader to the right place.
To link to an article where the title is not contained in your article's text, use the correct name, the pipe symbol ("|"), and what you want the text to look like, all within the link, like this:
[[Wilbur Shandlin (Jack) Jackson|Jackson’s]] track record is less than stellar, however.
Now what appears in the text is "Jackson's", but people who click the link will go to the fully-named page.