Function: Checks if a user is logged in, if not it redirects them to the login page.

Function: Ensures intent by verifying that a user was referred from another admin page with the correct security nonce.

Function: Verifies the Ajax request to prevent processing requests external of the blog.

Function: Retrieves the current user object.

Function: Retrieves info for user lists to prevent multiple queries by get_userdata().

Function: Sends an email, similar to PHP’s mail function.

Function: Logs the current user out.