A plugin is a piece of functionality that can be added to your Wordpress site by simply installing it with a few mouse clicks. Some plugins require additional configuration, but many work right out of the box. Examples of plugins include a Flash image slideshow, a function that automatically creates a new XML sitemap for [...]
Wordpress is completely customizable via plugins, and there are no design restrictions. What you can and can’t do with your site is governed completely by the hosting environment where your web site is located. Additionally, you can also have your own domain name, and integrate Wordpress with other web services and applications to extend its’ [...]
Its features are limited to exactly what you see, and your options for design changes are very limited (and usually not free) as well. Plugins are not an option with Wordpress.com, and you do not have your own domain name. Access to source code is minimal. Affiliate marketing is also not permitted on Wordpress.com.
Wordpress is a flexible open-source content management system that makes the task of changing content, adding new pages and complex functionality rather simple, enabling a wide range of users and operators to effectively use it.