A plugin is a type of Joomla extension which adds functions associated with trigger events. When a trigger event occurs, any active plugins associated with that event fire, allowing you to further extend the functionality of your site. There are many trigger events included with Joomla, though an extension can add custom events of its own.
The majority of the plugins available impact behind-the-scenes activity to Joomla and are virtually invisible to the user. Google Analytics scripting is a popular example of a useful plugin. By installing a plugin to add the Google Analytics code to every page as it loads, you do not have to edit the template source files to do so.
