reference/functions/domain_exists/) ` wp-includes/ms-functions.php ` |  Checks whether a site name is already taken.   
[ wpmu_welcome_notification() ](https://developer.wordpress.org/reference/functions/wpmu_welcome_notification/) ` wp-includes/ms-functions.php ` |  Notifies the site administrator that their site activation was successful.   
[ is_email_address_unsafe() ](https://developer.wordpress.org/reference/functions/is_email_address_unsafe/) ` wp-includes/ms-functions.php ` |  Checks an email address against a list of banned domains.   
[ wpmu_validate_user_signup() ](https://developer.wordpress.org/reference/functions/wpmu_validate_user_signup/) ` wp-includes/ms-functions.php ` |  Sanitizes and validates data required for a user sign-up.   
[ wpmu_validate_blog_signup() ](https://developer.wordpress.org/reference/functions/wpmu_validate_blog_signup/) ` wp-includes/ms-functions.php ` |  Processes new site registrations.   
[ wpmu_signup_blog() ](https://developer.wordpress.org/reference/functions/wpmu_signup_blog/) ` wp-includes/ms-functions.php ` |  Records site signup information for future activation.   
[ wpmu_signup_user() ](https://developer.wordpress.org/reference/functions/wpmu_signup_user/) ` wp-includes/ms-functions.php ` |  Records user signup information for future activation.   
[ wpmu_signup_blog_notification() ](https://developer.wordpress.org/reference/functions/wpmu_signup_blog_notification/) ` wp-includes/ms-functions.php ` |  Sends a confirmation request email to a user when they sign up for a new site. The new site will not become active until the confirmation link is clicked.   
[ wpmu_signup_user_notification() ](https://developer.wordpress.org/reference/functions/wpmu_signup_user_notification/) ` wp-includes/ms-functions.php ` |  Sends a confirmation request email to a user when they sign up for a new user account (without signing up for a site at the same time). The user account will not become active until the confirmation link is clicked.   
[ sanitize_bookmark_field() ](https://developer.wordpress.org/reference/functions/sanitize_bookmark_field/) ` wp-includes/bookmark.php ` |  Sanitizes a bookmark field.   
[ add_user_to_blog() ](https://developer.wordpress.org/reference/functions/add_user_to_blog/) ` wp-includes/ms-functions.php ` |  Adds a user to a blog, along with specifying the user’s role.   
[ WP_HTTP_IXR_Client::query() ](https://developer.wordpress.org/reference/classes/wp_http_ixr_client/query/) ` wp-includes/class-wp-http-ixr-client.php ` |   
[ get_bookmarks() ](https://developer.wordpress.org/reference/functions/get_bookmarks/) ` wp-includes/bookmark.php ` |  Retrieves the list of bookmarks.   
[ get_site_by_path() ](https://developer.wordpress.org/reference/functions/get_site_by_path/) ` wp-includes/ms-load.php ` |  Retrieves the closest matching site object by its domain and path.   
[ graceful_fail() ](https://developer.wordpress.org/reference/functions/graceful_fail/) ` wp-includes/ms-deprecated.php ` |  Deprecated functionality to gracefully fail.   
[ ms_site_check() ](https://developer.wordpress.org/reference/functions/ms_site_check/) ` wp-includes/ms-load.php ` |  Checks status of current blog.   
[ WP_Scripts::do_item() ](https://developer.wordpress.org/reference/classes/wp_scripts/do_item/) ` wp-includes/class-wp-scripts.php ` |  Processes a script dependency.   
[ WP_Scripts::all_deps() ](https://developer.wordpress.org/reference/classes/wp_scripts/all_deps/) ` wp-includes/class-wp-scripts.php ` |  Determines script dependencies.   
[ get_the_author_meta() ](https://developer.wordpress.org/reference/functions/get_the_author_meta/) ` wp-includes/author-template.php ` |  Retrieves the requested data of the author of the current post.   
[ the_author_meta() ](https://developer.wordpress.org/reference/functions/the_author_meta/) ` wp-includes/author-template.php ` |  Outputs the field from the user’s DB object. Defaults to current post’s author.   
[ get_the_author_link()