Wordpress is the most popular blog software on the web. Open source, this blog publishing application can also be used for content management.
If you want to start a new blog, you can create one on Wordpress for free. Their easy-to-use interface lets you start out a blog in less than an hour; really, it's more like 15 minutes. You can choose your blog name (as long as it is not used yet), choose your blog template, and blog's design theme.
Wordpress can be accessed in a hosting environment or downloaded/installed on a server. For beginners, the best option is free hosting service from Wordpress.com. Many shared web hosting services also offer automated WordPress installation through their control panel. Wordpress has enough flexibility so that both beginners and expert developers can use it and, more important, get it to do what they want. If you are comfortable with WordPress's interface but want to do more than blogging, Wordpress does offer its own web hosting service. And, again, Wordpress is usually installed on most web servers.