Categories (category)
| cat_is_ancestor_of() | Checks if the specified category is a child of another specified category (all nesting levels are checked). Conditional tag. |
| category_description() | Retrieve category description. |
| category_exists() | Checks whether a category exists. |
| get_cat_ID() | Retrieve the ID of a category from its name. |
| get_cat_name() | Gets the name of the category by the passed ID. |
| get_categories() | Gets categories as an array of objects. |
| get_category() | Retrieves category data given a category ID or category object. |
| get_category_by_slug() | Retrieve category object by category slug. |
| get_category_link() | Retrieve category link URL. |
| get_category_parents() | Retrieve category parents with separator. |
| get_the_category_by_ID() | Retrieve category name based on category ID. |
| in_category() | Check if the current post is within any of the given categories. |
| single_cat_title() | Display or retrieve page title for category archive. |
| wp_create_category() | Add a new category to the database if it does not already exist. |
| wp_dropdown_categories() | Display or retrieve the HTML dropdown list of categories. Instead of categories you can specify the name of an custom taxonomy. |
| wp_insert_category() | Inserts a new category into the database. Or updates an existing category by specifying a category ID. |
| wp_list_categories() | Displays a list of categories as HTML links. If you click on the link, all posts from the category will be shown. |