Debian is a Linux distribution, that is widely used for desktop machines, however it has been gaining popularity as a server OS during the last couple of years too. It is very stable and safe, as fixes are released in just a couple of days after a problem is discovered. Debian has a vast support community, so when you have any questions or problems with the OS or with any of the 30,000+ packages it includes, you will be able to contact the developers straight away through email using special mailing lists and receive a reply in just 15-20 minutes. The Debian community provides the top level of support possible, because all your questions will be handled by the same people who built Debian in the first place, so they have an in-depth knowledge of how their own system operates. As the Operating System is free to use and distribute, no license costs will be added to your web hosting fees and you'll be able to modify the code files and any other software that you install with no restrictions, so as to optimize the software environment for your sites. In addition, Debian performs very well on any kind of hardware, because it is light and quick and doesn't require much memory.