Alternative Menu Items are used and work the same way as standard menu items. Since they are already based on customised layouts, template overrides do not apply to alternative menu items.
Joomla uses groups as a method of assigning permissions. Default groups: Public, Guest, Manager, Administrator, Registered, Author, Editor, Publisher, Publisher, Super Users. However, you can create unlimited user-defined Groups.
Modules are lightweight and flexible extensions used for page rendering. These modules are often “boxes” arranged around a component on a typical page. A well-known example is the login module. Modules are assigned per menu item, so you can decide to show or hide (for example) the login module depending on which page (menu item) the user is currently on. Some modules are linked to components: the “latest news” module, for example, links to the content component (com_content) and displays links to the newest content items. However, modules do not need to be linked to components; they don't even need to be linked to anything and can be just static HTML or text. Modules are managed in the Joomla! Administrator view by the Module Manager. Joomla default modules: Archived Articles? Articles – Newsflash Articles – Related Articles Articles – Categories Articles Category Banners? Breadcrumbs Custom HTML Random Image Search? Statistics Syndication Feeds Feed Display Footer? Language Switcher Latest News Latest Users Login? Menu? Most Read Content Weblinks Who’s Online Wrapper Reference: http://docs.joomla.org/Glossary
