Joomla Extensions

Joomla is one of the most popular Content Mangement Systems (CMS) on the market.  It's used on many high-profile websites and is generally known for being both robust through it's vast ecosystem of Joomla extensions, yet relatively easy to configure.  Due to the difficulty of administration with more technical CMS's like Drupal, or more sandboxed approch such as WordPress, Joomla is a great, well-rounded alternative to the other available options.  However, that's not to say that it's perfect for every scenerio.

Joomla Extension Types

Joomla extensions are divided into 4 main types: Components, Modules, Plugins (Mambots in Joomla 1.0), and Templates.  Each serves a different purpose within the Joomla ecosystem, so we'll explore each in detail below, and build up as we progress.

Joomla Templates

Theming within Joomla is similar to other CMS's in that you can apply a template to your site, and immediately it will take on a new look and feel.  Templates are comprised of some PHP files along with images and stylesheets in order to create this new look for your website.  In general, they will apply custom looks to each of the modules, components, and general HTML features such as text and tables throughout your site.

Additionally, a template specifies where the component (1 per page) and modules (many per page) appear.  The module positions are specified by the template, with common ones being "top", "left", "right", and "bottom".  Within these positions, you can place any modules to customize the 'outside' of your site.

Be aware that Joomla templates are mostly 'generic' in that they do not customize any specific developer's component or modules.  The developer themself is responsible for using the built-in Joomla stylings (which a template does alter) or providing it's own styles.

Joomla Plugins (1.5) or Mambots (1.0)

Plugins for Joomla are custom pieces of code meant to modify a rendered page or do other 'background' work.  They may or may not have a visual impact on your site.

Some examples of Joomla plugins are for authentication purposes, which are called when a user logs into your site.  Joomla authenticatication plugins are responsible for checking the username and password against the local Joomla database or against an external sources such as Open ID or Gmail authentication.

Another plugin example is the CMS Market Product Widget.  It automatically scans every page that is rendered from your site for a specific tag such as {cmsmarketproduct 22}.  When encountered, it removes the tag and replaces it with product information pulled from the CMS Market website.  Content plugins all occurs behind the scenes to the user, and are a great way to modify your page in dynamic ways.

Joomla Modules

As described above, within each template there are different placement configurations for where modules can be placed.  A Joomla Module outputs HTML into the area specified and are instrumental to navigating, customizing, and providing extra information on your site.  While only one component is displayed on a page at a time, many modules can be displayed.  This allows modules to help guide your visitors to other areas of your site by displaying information from other components that the user may want to see more information about.

Joomla modules are very diverse, but some primary examples are of the Menu Module which let's you select a menu configured within your site and display it.  Module parameters give you the option of specifying whether the menu's are displayed horizontally or vertically, how deep the menu should show, any custom styles that should be applied, and many more.  Another extremely common one is the login module which allows users to log in and out of your site while on any page.

A Joomla module can display information that is provided from a component installed on your site or it can be a completely standalone feature.  For example, a 'visitor counter' module may not have a corresponding component, but an event calendar would have modules so you can display 'upcoming events' on any page you wish.

Finally, in addition to placing modules in varied positions on your page, modules can be easily set to display on only select pages within your site.  This allows for making each section of your site unique and relevant to the content you want to display to the user.

Joomla Components

Joomla components are the grandaddy extension in the Joomla ecosystem.  In many cases, they include modules and/or plugins in order to integrate themselves with your page in the best ways possible.  Almost all Joomla components create tables in the database to store their information and have a configuration area in the administration area of your site to change their functionality suit your site. Joomla limits the display to one component per page.  This allows for one component to control the overall look of the main area of the page it is displayed on in order to best convey itself to the user.