"WordPress is a state-of-the-art semantic personal publishing platform with a focus on aesthetics, web standards, and usability. What a mouthful. WordPress is both free and priceless at the same time. - WordPress.org"

WordPress is a blogging platform just like Blogger or BlogDrive. The difference is that WordPress software can be download and install to your own webhosting. Blogger or BlogDrive doesn't offer that kind of tools. WordPress is built on PHP and MySQL technology. So your can install those WordPress system even on your local pc as long as you have PHP and MySQL installed! And also you can install themes on WordPress.

Nevertherless, blogging is even easier for me using Blogger. No need to install. Even JUNAIDIX.NET and Msjbox is using blogger!

More Info:
WordPress.org
WordPress.com

Related Blogging Tools:
Blogger.com
BlogDrive.com
LiveJournal
MovableType