12WordPress
WordPress is an open source blog publishing application and can be used for basic content management. It was first released in May 2003 by its co-founders Matt Mullenweg and Mike Little as the successor to b2/cafelog. It is powered by PHP and a SQL data backend. As of September 2009, Wordpress is used by 62.8 million websites in the US and 202 million websites worldwide.
More information? Visit the official website: www.wordpress.org
source: Wikipedia