WordPress is famous text blog system. It is built in PHP language. It's developer name is Michel Valdrighi. WordPress also provides you free and open source codes for your own site. Any one with limited knowledge can install Word Press. Word Press needs PHP enabled server and MySQL database. All posts and data stored in MySQL tables.

You can download free and latest source codes at
http://www.wordpress.org/download/

WordPress is distributed under GNU General Public License 2.0. It's name was suggest by Christine Selleck (friend of main developer Matt Mullenweg).

http://www.wordpress.com is another site. It provides free blog to everyone. Any one can register and create free blog with sub domain like anyname.wordpress.com. This site was released for beta at 08-August-2005 and was open for public at 21-November-2005. Now it has over 3.5 million blogs.

WordPress.com is not 100% free. It provides more storage, domain mapping and CSS editor only for paid users. It's financial support is Google Adsense and paid up gradations.

Initially this service was not open. It was invitation only service but later it become open registration service.

To view posts there is no need to register or login but blog owner can restrict any post with password. If you want to post new post then login and registration is compulsory.

WordPress also provides an Administrator portion where blog owners can add more themes and plug ins into their blogs. Themes and Templates are new designs for WordPress blogs. Blog owners can change design by using WordPress Template or themes. Plug ins are new functionality added to the WordPress blogs.