Debian is a Linux distribution, which is widely used for desktop computers, yet it has been becoming more popular as a server OS during the last few years as well. It is really stable and risk-free, since fixes are released within a couple of days after an issue is discovered. Debian has a large support community, so if you have any kind of questions or problems with the OS or with some of the 30,000+ packages it features, you can easily contact the developers straight away through e-mail using special e-mail lists and receive a response in 15-20 minutes. The Debian community offers the best level of support possible, since your questions will be handled by the very same people who built Debian in the first place, so they have an in-depth knowledge of how their own system works. Since the Operating System is 100% free to use and distribute, no license costs will be added to your hosting fees and you will be able to modify the code files and any other software that you install without restrictions, to optimize the software environment for your websites. Furthermore, Debian performs very well on any hardware, because it's light and quick and doesn't require much memory.