Drupal is a great Content Management System (CMS) to build all kinds of websites; from simple personal blogs to advanced corporate web applications. There is a huge number of add-ons, plugins or modules available that will build you any site you can possibly dream of. Drupal is a license free, Open Source CMS. It is as flexible as robust, and constant improved by hundreds of thousands of dedicated people all over the world.
There are thousands of websites that run on Drupal 6 Core. If you are thinking about upgrading, or modernizing, your existing website, though, Drupal 7 is recommended. Doubting wich version benefits you, our your company, at best? Let's have a coffee, and we'll find out. Soon.