The Drupal Menu System handles both the navigational system (visible menus and links) as well as the Drupal callbacks in the back end. The menu links listed on the header of a Drupal site is normally the primary menu or the secondary menu. These menus are sets of static links that you create via the Drupal admin interface. However sometimes it is useful to have a login / logout link in the primary or the secondary menu depending on whether the user is logged out or logged in. Here is how you add this.