Wikipedia:Tip of the day/July 31, 2007
Sometimes it is useful to provide links to categories, such as in the lists of category links found on portals, or when mentioning a category in a message. But many Wikipedians try to write a category name only to find that they have categorized the page they are editing. For example, if one writes "I think [[Category:Living people]] would be appropriate", it will appear as "I think would be appropriate" and the page will be added to the Living people category. The category link itself disappeared! It disappeared because Wikipedia automatically placed it in the category bar at the bottom of the page, thus entering it as an article in the category system.
In order to provide a link to a category without this happening, simply add a colon after the first set of square brackets. Then "I think [[:Category:Living people]] would be appropriate", appears as "I think Category:Living people would be appropriate".
You can also use {{cl}}, but this is less common.