The way it works, using modules and extensions, allows you to create just about any type of website depending on your needs, from a blog to a news site, an online store or a simple corporate introduction page.
Among its other strengths is that it's free under a GNU license, it has a large community of users, help forums and constant new updates and extensions; therefore making it, together with Wordpress and Drupal, one of the most used and versatile CMS' in the world.
Given its business-oriented origins, it’s perfect for managing inventories and large quantities of information. One the other hand, it isn't as direct or simple as Wordpress, and it requires a greater command of the tool if you want to apply SEO techniques to your website.
Requires a database and and HTTP Apache server.