Codex tools: Log in
Load the auth check for monitoring whether the user is still logged in.
Can be disabled with remove_action( 'admin_enqueue_scripts', 'wp_auth_check_load' );
This is disabled for certain screens where a login screen could cause an inconvenient interruption. A filter called wp_auth_check_load can be used for fine-grained control.
wp_auth_check() is located in
Function ref links