Plugins are new to Drupal in its latest version and are an elegant solution to an important problem--the encapsulating and reusing functionalities. Right off the bat, you should not confuse them with things such as the WordPress plugins, which are more akin to Drupal modules. Instead, you should think of plugins as components of reusable code that can be used and managed by a central system. They are typically used to allow others to contribute their own distinct functionality within your own system. Looking at it from the other direction, Drupal core, for example, handles many things in a certain way, but allows you to provide your own plugins to handle those things in a different way.
An interesting way of looking at plugins is ...
