WordPress is designed to be a small compact CMS system that still provides a large amount of functionality as standard but more importantly provides a framework where plugins can simply be added that extend the functionality so that a website built using WordPress can do almost anything you can imagine. The other major benefit of plugins is that the WordPress core code as well as each and every individual plugin can be independently upgraded without affecting any other part of the system. There are many thousands of different plugins written by an equally large number of people with a varied level of skill ! There are many repositories that list plugins and often provide independent rankings and reviews and also list details such as when it was last updated (you rarely want to be installing a plugin that isnt regularly updated) – if you plan to add a plugin to your WordPress system take care to read these carefully !