Help:Categories
Categories are a way to group pages and make the wiki easier to navigate. They can be found at the bottom of the page.
Categories link together in a category tree, which you can view here: Special:CategoryTree. It is important to have categories so that pages can be grouped together; a lot of maintenance activities or bot usage relies on categories to organize pages or templates.
To add a category on a page, simply type [[Category:<Category name>]]. Our naming convention is to use sentence case for categories. The wiki editor will offer autocompletion suggestions of the category name once you have typed enough letters.
If you need to link to a category on a page without putting that page in that category you can type [[:Category:<Category name>]]. However, this should be rare; when in doubt, do not do this.
How to create a category
If you can't find a category that fits a page, feel free to ask an administrator - categories are useful, but they are more useful when they are apt. If you do need to create a category, make sure to link it in the structure. An unlinked category will show as a redlink, just as any other link. You may put one category in multiple other categories.
For example, when Exandria Unlimited: Calamity started, we created the category Category:Ring of Brass to group the PCs. We then put this in the categories Category:Adventuring parties and Category:Avalir.
How categories work
Categories are also pages like regular articles, but they also serve an important grouping function for articles, templates, files and even other categories. If an article is added to a category whose page hasn't been created, it still counts as a member of that category. You can see a list of all such red-linked categories on Special:WantedCategories; we try to keep this list to a minimum, so please feel free to create one of these categories if there are enough potential category members listed. Conversely, Special:UnusedCategories highlights existing categories that currently have zero members, which might be good candidates for deletion.
When to add a category to a page
Sometimes, infoboxes or templates on a page will automatically add it to a category, so that if you edit a page you will not be able to edit its category membership directly. For example, the appearance template automatically adds characters to the appropriate sub-categories of Category:Characters by media, such as Category:Characters in Campaign 1. However, most categories are added manually through the creation method mentioned above.
If you're creating a new article and want to add it to categories, browsing the structure starting at Category:Content might be useful. Try to put pages in the most specific category possible without adding them to higher-level categories. For example, Nicodranas is a city on the shore of the Menagerie Coast, which itself is on the continent of Wildemount. The category that contains cities, Category:Settlements, breaks them down by geographical region. Nicodranas only needs to be added to Category:Settlements on the Menagerie Coast and does not need to be added to the broader Category:Settlements in Wildemount.
However, sometimes, a category is added to both its most specific sub-category and the containing for that sub-category when the containing category would be useful as a complete set. This most often (and always) happens with articles that have categories with the same name, i.e. Nicodranas should be in both Category:Nicodranas and Category:Settlements on the Menagerie Coast even though Category:Nicodranas is already a sub-category of that category. Other articles may be affected, particularly if it would feel like an oversight to not have an article or category in the larger category. For example, Category:Images of Fjord is in both Category:Images of player characters and Category:Images of the Mighty Nein, a sub-category of Category:Images of player characters, because it is useful to have all player characters listed in the larger category as well and it would otherwise feel incomplete or be more inconvenient for people to access the entire set by clicking through multiple categories; these instances are left to case-by-case judgment.
To see a list of all articles that have not been added to any categories yet, see Special:UncategorizedPages. They could use some "categorical" attention.
Other useful links
We have HotCat enabled as a wiki extension; check out the documentation!