Taxonomies (Categories, Tags) (category)
| _update_post_term_count() | Updates the number of posts attached to a term (taxonomy element). The types of posts to consider are taken from the taxonomy settings. |
| get_ancestors() | Gets the IDs of the parent elements of the specified object (page, taxonomy, category). |
| get_term_parents_list() | Gets the list of parents of the specified term (taxonomy element). |
| wp_get_split_terms() | Gets data about taxonomy terms that had the same ID and were split since WP version 4.2. |
| WP_Tax_Query{} | The class creates the JOIN and WHERE parts of the SQL query, which, in addition to the main query, will filter the result by the specified terms (taxonomy elements). |
| wp_terms_checklist() | Displays/retrieve the UL list of checkbox input elements input type="checkbox" labelled with term names. |
Metadata (termmeta)
| add_term_meta() | Adds a meta-field (additional field) for the specified taxonomy term (categories, tags ...). |
| delete_term_meta() | Deletes the specified meta-field of the specified taxonomy term. |
| get_term_meta() | Gets the value of the specified meta-field of a taxonomy term (categories, tags, etc.). You can get all values as an array. |
| has_term_meta() | Gets all metadata of the specified taxonomy element (term). |
| register_term_meta() | Registers a meta-field for the specified taxonomy. |
| update_term_meta() | Updates the metadata of a taxonomy term (categories, tags ...). |
Categories
| 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() | Gets the description of the category, which is specified on the category editing page in the admin panel (posts > categories). |
| category_exists() | Checks if the specified category exists. If it does, it returns the ID of that category. |
| get_cat_ID() | Gets the category ID by the given 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() | Gets data of the specified category. |
| get_category_by_slug() | Gets category data by its alternative name (slug). |
| get_category_link() | Gets the correct link to the category page by the given category ID. |
| get_category_parents() | Gets a list of parent categories of the current category. The list is displayed in hierarchical order. |
| get_the_category_by_ID() | Gets the category name by the given ID. |
| in_category() | Checks whether the current (or specified) post belongs to the specified category (multiple categories can be specified). Conditional tag. |
| single_cat_title() | Displays the title of the category or tag. Used outside the loop. Intended for archive pages. |
| wp_create_category() | Simplified function for adding a category, which requires the name of the new category and, if needed, the ID of the parent category. |
| 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. |
Tags
| edit_tag_link() | Outputs a link to edit the current meta-field if the user is allowed to modify tags. |
| get_tag_link() | Retrieves the link to the tag by given tag ID. |
| get_tags() | Retrieve an array of tags objects. Tags can be retrieved by different criteria (see $args parameter). |
| single_tag_title() | Outputs the title of the current meta-field if the tag archive page is being viewed. |
| tag_description() | Gets the description of the tag, which is set when creating/editing the tag in the admin panel. |
| tag_exists() | Checks if the specified tag exists. If it exists, it returns the ID or an array of data for that tag. |
| wp_generate_tag_cloud() | Processes the provided term (tag) data and returns the HTML code for the tag cloud. |
| wp_tag_cloud() | Outputs or retrieves a tag cloud (a list of tags in the form of a cloud). You can specify any taxonomy. |
Taxonomies: categories, tags, ...
| edit_term_link() | Displays/retrieves edit term link (html tag A), link to edit the specified taxonomy element. |
| get_edit_term_link() | Gets the URL for editing the specified taxonomy term. |
| get_taxonomies() | Gets the list of registered taxonomies. You can restrict the list to the desired parameters. |
| get_taxonomy() | Gets an object containing settings (data) of the specified taxonomy. |
| get_term() | Gets data about a taxonomy element (term) by the provided ID. |
| get_term_by() | Gets the specified term (taxonomy element) by: name, slug, or term ID. |
| get_term_children() | Gets all child elements of the specified taxonomy element (categories) as an array. |
| get_term_field() | Gets the term field. The field is sanitized by the function sanitize_term_field(). |
| get_term_link() | Gets the URL for the archive page of a term (taxonomy item). The same as the link to the category page. |
| get_terms() | Retrieve the terms (items) of a given taxonomy or list of taxonomies by the given parameters. |
| is_taxonomy_hierarchical() | Checks if the specified taxonomy is hierarchical. Conditional tag. |
| register_taxonomy() | Creates a new custom WordPress taxonomy. Allows you to change an existing taxonomy. |
| register_taxonomy_for_object_type() | Binds (adds) the specified taxonomy to the specified post type. |
| sanitize_term() | Sanitize all fields of the taxonomy element (term) using the sanitize_term_field() function. |
| sanitize_term_field() | Prepares (cleanse) term field value for use it in a text or elsewhere (depends on cleaning context). |
| single_term_title() | Display or retrieve title for the current taxonomy (category, tag, etc.). Uses on term archive pages. |
| taxonomy_exists() | Checks if the specified taxonomy exists. |
| term_description() | Gets the description of the term (taxonomy element: tags, categories, etc.) that is specified on the term creation/editing page. |
| term_exists() | Check if a given taxonomy element exists. Returns either term ID or a term data if the element (term) exists. |
| term_is_ancestor_of() | Checks if the second term is a child of the first (all levels of nesting are checked). Conditional tag. |
| the_terms() | Outputs a list of links to terms (taxonomy elements) related to the specified post. |
| unregister_taxonomy() | Cancels the registration of the specified taxonomy (removes the taxonomy). |
| unregister_taxonomy_for_object_type() | Unlinks the taxonomy from the specified post type (or other object). |
| wp_count_terms() | Counts how many elements (terms) are in the taxonomy, with or without posts. |
| wp_delete_term() | Deletes a term (category, tag) from the Database. |
| wp_get_term_taxonomy_parent_id() | Gets the ID of the parent element of the taxonomy (term) for the specified one. |
| wp_insert_term() | Adds a new taxonomy element (term, category) into a database. |
| wp_update_term() | Updates the term (taxonomy element) using the specified data. |
| wp_update_term_count() | Updates/recalculates the number of posts in a taxonomy element (term). |
For posts
| get_object_taxonomies() | Gets the taxonomies related to the specified post type or the passed object. |
| get_objects_in_term() | Gets the IDs of objects (usually posts) that relate to the specified element of the specified taxonomy. |
| get_the_category() | Gets an array of categories data related to current post. |
| get_the_category_list() | Retrieve links to the categories to which the post belongs in either HTML list or custom format. |
| get_the_tag_list() | Gets the HTML string of tags for the current post. The name of each tag will be a link to the archive of posts with that tag. Used in a loop. |
| get_the_tags() | Retrieve an array of post tags. Each array element is a WP_Term object. Can be used within The Loop. |
| get_the_taxonomies() | Retrieve all taxonomies associated with a post. Gets an array of HTML links. |
| get_the_term_list() | Displays a list of links to taxonomy elements (e.g. tags) related to a specified post. |
| get_the_terms() | Gets the taxonomy elements (terms) that are attached to the specified post. |
| has_category() | Checks whether the current or specified post has at least one of the specified categories. |
| has_tag() | Checks if the current post has any of the given tags. A conditional tag. |
| has_term() | Checks if the specified post is associated with the specified taxonomy terms. |
| is_object_in_taxonomy() | Checks if the specified post type is associated with the specified taxonomy. |
| is_object_in_term() | Defines whether the specified object is associated with any of the specified taxonomy elements (term). Specific term(s) can be provided to check the association. |
| the_category() | Displays links to the categories to which the post belongs in either HTML list or custom format. |
| the_tags() | Retrieve the tags links for a post. |
| the_taxonomies() | Display links to taxonomy terms of the current post. Used inside WordPress loop |
| wp_delete_object_term_relationships() | Destroys all relationships of the object (post, page) with the specified taxonomy(ies). |
| wp_get_object_terms() | Gets the terms (taxonomy elements) related to the given object(s) (posts) in the specified taxonomy. |
| wp_get_post_categories() | Gets the list of post categories as an array. |
| wp_get_post_tags() | Gets a list of tags for a specified post as an array. |
| wp_get_post_terms() | Gets the elements of the specified taxonomy (tag, category) to which specified post is associated. |
| wp_remove_object_terms() | Breaks the connection between the specified object and the specified term, i.e., removes the post from the taxonomy element (category). |
| wp_set_object_terms() | Attaches a post to a term (taxonomy element). For example, places a post in the specified category. |
| wp_set_post_categories() | Sets categories for a post. |
| wp_set_post_tags() | Sets tags for a post. |
| wp_set_post_terms() | Sets the terms for specified post (sets categories for post). |