Out of the box, Joomla does a great job of managing the content needed to make your website sing. But for many people, the true power of Joomla! lies in the application framework that makes it possible for thousands of developers around the world to create powerful add-ons that are called extensions. An extension is used to add capabilities to Joomla! that do not exist in the base core code. Here are just some examples of the hundreds of available extensions:

• Dynamic form builders
• Business or organisational directories
• Document management
• Image and multimedia galleries
• E-commerce and shopping cart engines
• Forums and chat software
• Calendars
• Email newsletters
• Data collection and reporting tools
• Banner advertising systems
• Paid subscription services
• and many, many more

You can find more examples over at our growing Joomla! Extensions Directory. Prepare to be amazed at the amount of exciting work produced by our active developer community!

A useful guide to the extension site can be found at:
http://extensions.joomla.org/content/view/15/63/

Types of Extensions

There are five types of extensions:

• Components
• Modules
• Templates
• Plugins
• Languages

You can read more about the specifics of these using the links in the article table of contents (another useful feature of Joomla!) at the top right or by clicking on the next link below.

Components

A component is the largest and most complex of the extension types. Components are like mini-applications that renders the main body of the page. An analogy that might make the relationship easier to understand would be that Joomla! is a book and all the components are chapters in the book. The core content component (com_content), for example, is the mini-application that handles all core content rendering just as the core registration component (com_user) is the mini-application that handles user registration.

Many of Joomla's core features are provided by the use of default components such as:

• Contacts
• Front Page
• Newsfeeds
• Banners
• Mass Mail
• Polls
• RSS Syndication

A Component will manage data, set displays, provide functions and in general can perform any operation that doesn't fall under the general functions of the core code.

Components work hand in hand with Modules and Plugins to provide a rich variety of content display and functionality aside from the standard article and content display. Components make it possible to completely transform Joomla and greatly expand its capabilities.

More information on components is available from the Joomla! help manual: Components
http://help.joomla.org/content/view/77/153/

Modules

A more lightweight and flexible extension used for page rendering is a module. Modules are used for small bits of the page that are generally less complex and able to be seen across different components. To continue in our book analogy, a module can be looked at as a footnote or header block, or perhaps an image/caption block that can be rendered on a particular page. Obviously you can have a footnote on any page but not all pages will have them. Footnotes also might appear regardless of which chapter you are reading. Simlarly modules can be rendered regardless of which component you have loaded.

Modules are like little mini-applets that can be placed anywhere on your site. They work in conjunction with components in some cases and in others are complete stand alone snippets of code used to display some data from the database such as Content (Newsflash) Modules are usually used to output data but they can also be form items to input data (Login Module and Polls as an example)

Modules can be assigned to module positions which are defined in both your template and backend under the Site/Template Manager/Module Positions menu items. For example, "left" and "right" are common for a 3 column layout.

Displaying Modules

Each module is assigned to a module position on your site. If you wish it to display in two different locations you must copy the module and assign the copy to display at the new location. You can also set which menu items (and thus pages) a module will display on. You can select all menu items or you can pick and choose specific menu items by holding down the control key and selecting multiple menu items one by one in the Modules Edit screen

Note your Main Menu is a Module! When you create a new menu in the menu manager you are actually copying the Main Menu module code and giving it the name of your new menu. When you copy a module you do not copy all it's parameters you simply allow Joomla to use the same code with two separate settings.

NewsFlash Example

NewsFlash is a Module which will display content items from your site in an assignable module position. It can be used and configured to display one category, all categories or to randomly choose content items to highlight to users. It will display as much of an article as you set, and will show a "read more" link to take the user to the full page.

The Newsflash component is particularly useful for things like Site News or to show the latest content item added to your site.

More information on Modules is available from the Joomla! help manual: Modules
http://help.joomla.org/content/view/91/153/

Plugins

One of the more advanced extensions for Joomla! is the plugin (formerly called a mambot). In previous versions plugins were known as mambots. Along with the development of Joomla! 1.5, mambots have been renamed to plugins and their functionality has been expanded. A plugin is a section of code that runs when a pre-defined event happens within Joomla! Editors are plugins, for example, that execute when the Joomla! event "onGetEditorArea" occurs. Using a plugin allows a developer to change the way their code behaves depending upon which plugins are installed to react to an event.

More information on Plugins is available from the Joomla! help manual: Plugins
http://help.joomla.org/content/view/110/153/

Languages

New to Joomla! 1.5 and perhaps the most basic and critical extension is a language. Languages are packaged as either a core language pack or an extension language pack. They allow both the Joomla! core as well as third party components and modules to be internationalised.

More information on languages is available from the Joomla! help site: Language Packs and Localised Releases
http://help.joomla.org/content/view/1651/243/

Got a question? With more than 100,000 members, the online forum at Joomla.org are a great resource for both new an experienced users. Go ahead, ask your toughest questions, the community is waiting to see what you're going to do with your Joomla! site.

Do you want to show off your new Joomla website? Go ahead, we have a section dedicated to that on our forum.

Do you want to join in?

If you think working with Joomla! is fun, wait until you start working on it. We're passionate about helping Joomla! users make the jump to becoming contributing members of the community, so there are many ways you can help Joomla's development:

• Submit news about Joomla!. We syndicate all Joomla! related news on our news portal. If you have some Joomla! news that you would like to share with the community, please submit your short story, article, announcement or review here.
• Report bugs and request features in our trackers. Please read Reporting bugs, for details on how we like our bug reports served up
• Submit patches for new and/or fixed behavior. Please read Submitting patches, for details on how to submit a patch.
• Join the developer forums and share your ideas for how to improve Joomla!. We're always open to suggestions, although we're likely to be skeptical of large-scale suggestions without some code to back it up.
• Join any of the community working groups and bring your personal expertise to the Joomla! community. More info about the different working groups can be found here.

That's all you need to know if you'd like to join the Joomla! development community.