Components are larger extensions that produce the major content for your site. Each component has one or more "views" that control how content is displayed. In the Joomla administrator there are additional extensions such as Menus, Redirection, and the extension managers.
Modules are small blocks of content that can be displayed in positions on a web page. The menus on this site are displayed in modules. The core of Joomla! includes 24 separate modules ranging from login to search to random images. Each module has a name that starts mod_ but when it displays it has a title. In the descriptions in this section, the titles are the same as the names.
Content modules display article and other information from the content component.
User modules interact with the user system, allowing users to login, show who is logged-in, and showing the most recently registered users.
These modules display information from components other than content and user. These include weblinks, news feeds and the media manager.
Utility modules provide useful functionality such as search, syndication and statistics.
Navigation modules help your visitors move through your site and find what they need.
Menus provide your site with structure and help your visitors navigate your site. Although they are all based on the same menu module, the variety of ways menus are used in the sample data show how flexible this module is.
A menu can range from extremely simple (for example the top menu or the menu for the Australian Parks sample site) to extremely complex (for example the About Joomla! menu with its many levels). They can also be used for other types of presentation such as the site map linked from the "This Site" menu.
Breadcrumbs provide users with information about where they are in a site.
Templates give your site its look and feel. They determine layout, colours, typefaces, graphics and other aspects of design that make your site unique. Your installation of Joomla comes prepackaged with three front end templates and two backend templates. Help
Joomla! installs in English, but translations of the interfaces, sample data and help screens are available in dozens of languages. Help
If there is no language pack available for your language, instructions are available for creating your own translation, which you can also contribute to the community by starting a translation team to create an accredited translation.
Translations of the interfaces are installed using the extensions manager in the site administrator and then managed using the language manager.
If you have two or more languages installed you may enable the language switcher plugin and module. They should always be used together. If you create multilingual content and mark your content, menu items or modules as being in specific languages and follow the complete instructions your users will be able to select a specific content language using the module. By default both the plugin and module are disabled.
Joomla 2.5 installs with a language override manager that allows you to change the specific words (such as Edit or Search) used in the Joomla application.
There are a number of extensions that can help you manage translations of content available in the Joomla! Extensions Directory.