WordPress
WordPress is an Open Source content management system used to build blogs and websites.
100% Free
WordPress
Open Source
You are free to extend it or modify the WordPress code in any way or use it for commercial projects without any licensing fees.
Themes
WordPress has thousands of different themes that can be used to change the layout of your website. This particular website uses the popular Thesis theme.
Templating system
Changes you make to your templates are reflected immediately on your site. There is no need for regenerating static pages.
Plugins
Best part of WordPress is hundreds of different plugins that can be used to add features for your website.
More information about WordPress