Help:Categories/Add a Page to a Category
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To add a page or uploaded file to a category, simply edit the page and add the following text (where NAME is the name of the category you want to add it to).
[[Category:NAME]]
Any number of Category tags may be added to the page and the page will be listed in all of them. Category tags can be added wherever you like in the editing text, but they are usually added at the very bottom for the convenience of other editors.
Spaces and line breaks before categories are ignored, thus
* A list item [[Category:Some category]] Some text
will be rendered the same as
* A list item Some text
You will need to manually add a <br /> tag or a line break after the category.