The menu bar contains all of the drop-down menus and submenus in your application. Each menu in the menu bar is represented by its menu title.
Submenus, or drop-down menus, are additional menu items that appear within a menu item. Submenu items appear when you hover or click on the menu item on the top-level menu or submenu level. Depending on the style of the menu, an arrow or some other graphic is used to indicate when the menu item opens the submenu items. A submenu can have a submenu and so on.