Wordpress

WordPress is an open source Content Management System (CMS), often used as a blog publishing application, powered by PHP and MySQL. It has many features including a plug-in architecture and a template system. WordPress is used by over 13% of the 1,000,000 biggest websites.

It was first released on May 27, 2003. As of February 2011, version 3.0 had been downloaded over 32.5 million times.

Features
WordPress has a web template system using a template processor. Users can re-arrange widgets without editing PHP or HTML code; they can also install and switch between themes. The PHP and HTML code in themes can also be edited for more advanced customizations. WordPress also features integrated link management; a search engine-friendly, clean permalink structure; the ability to assign nested, multiple categories to articles; and support for tagging of posts and articles. Automatic filters are also included, providing standardized formatting and styling of text in articles (for example, converting regular quotes to smart quotes). WordPress also supports the Trackback and Pingback standards for displaying links to other sites that have themselves linked to a post or article.

Finally, WordPress has a rich plugin architecture which allows users and developers to extend its functionality beyond the features that come as part of the base install.
Native applications exist for Android, iPhone/iPod Touch, Windows Phone 7 and BlackBerry which provide access to some of the features in the WordPress Admin panel and work with WordPress.com and many WordPress.org blogs.