Assigining your articles to corresponding categories is very important for helping your visitors navigate your MediaWiki site with ease. Thankfully, MediaWiki comes with an included system for handling categories.
To add an article to a category:
Simply edit the article you want to add to the category, and add the following line at the end of the contents:
[[Category: Nameofcategory]] (where Nameofcategory is your category name)
It doesn’t matter if the category does not exist or was never used before. MediaWiki will create a new page for each category containing all of the articles that were added to it.