Generally you will tag a page without putting a visible link on it.
The [[tag_plugin|plugins/tag]] allows you to do so, like this:
- \[[tag mytag othertag thirdtag]]
+ \[[!tag mytag othertag thirdtag]]
You can also tag a page with a visible link:
- \[[taglink mytag]]
+ \[[!taglink mytag]]
This tag will be displayed just like a regular [[ikiwiki/WikiLink]].