<translate> A plugin is a kind of Joomla! extension. Plugins provide functions which are associated with trigger events. Joomla provides a set of core plugin events, but any extension can fire (custom) events. When a particular event occurs, all plugin functions of the type associated with the event are executed in sequence. This is a powerful way of extending the functionality of the Joomla! Platform. It also offers extension developers a way to allow other extensions to respond to their actions, making extensions extensible.
The Joomla! plugin architecture follows the Observer design pattern. The JPlugin class provides the means to register custom plugin code with core or custom events. The JDispatcher class (JEventDispatcher in Joomla 3.x) is an event handler which calls all plugins registered for a particular event, when that event is triggered.
Useful reference: Gallery 2: Embedding: Event-Based Loose-Coupled Integration
The following articles will help familiarise you with Joomla! plugins. They are a good starting point to understanding and then developing plugins.
To understand how to install and use a plugin in Joomla it is recommended to read Administration of a Plugin in Joomla
To understand plugins better it is advised that you create a basic plugin for Joomla!.
It is also advised to read on how to run a basic content plugin in a custom module or component you may have already developed it is recommended to read Triggering content plugins in your extension.
To understand the principles on which the Plugin system works Plugin Developer Overview. To then implement this in a component you have designed it is recommended to read Supporting plugins in your component.
For more developer information, see Plugin Development.
Joomla! ships with a variety of core events, organised into groups. These are described in the following topics.