Debian is a Linux distribution, that is widely used for desktop computers, but it's been gaining in popularity as a server OS over the last few years too. It's very stable and protected, due to the fact that fixes are released in a couple of days after a problem is discovered. Debian has a large support community, so if you have any kind of questions or problems with the OS or with any of the 30,000+ packages it features, you can contact the developers directly through e-mail using special mailing lists and receive a response in just 15-20 min. The Debian community gives you the top level of support possible, as all your questions will be handled by exactly the same people who built Debian in the first place, so they have an in-depth knowledge of how their system operates. As the Operating System is free to use and distribute, no license costs will be added to your website hosting fees and you can customize the program code files and any additional software which you install with no restrictions, to optimize the software environment for your sites. Furthermore, Debian performs very well on any kind of hardware, as it is light and efficient and doesn't require a lot of memory.