Debian is a Linux distribution, which is preffered for desktop machines, but it has been gaining in popularity as a server OS over the last couple of years as well. It is really stable and secure, due to the fact that fixes are released within a few days after a problem is discovered. Debian has a large support community, so when you have any kind of questions or issues with the OS or with some of the 30,000+ packages it includes, you can easily contact the developers directly through electronic mail using special mailing lists and receive a reply in just 15-20 minutes. The Debian community gives you the best level of support possible, because all of your questions will be handled by the very same people who made Debian in the first place, so they have a detailed knowledge of how their own system functions. Since the Operating System is free to use and distribute, no license costs will be added to your website hosting fees and you can modify the program code files and any other software which you install without restrictions, so as to optimize the software environment for your sites. In addition, Debian performs very well on any hardware, because it is light and quick and does not need a lot of memory.