Debian is a Linux distribution, that's widespread for desktop machines, but it has been gaining in popularity as a server Operating System during the last few years as well. It is really stable and risk-free, as fixes are released within a couple of days after a problem is discovered. Debian has a vast support community, so if you have any questions or issues with the OS or with some of the 30,000+ packages it is equipped with, you're able to contact the developers directly via email using special e-mail lists and receive a response in 15-20 minutes. The Debian community gives you the best level of support possible, as your questions will be handled by the very same people that built Debian in the first place, so they have a thorough knowledge of how their own system functions. As the Operating System is free to use and distribute, no license charges will be added to your hosting fees and you'll be able to change the code files and any additional software that you install with no restrictions, to optimize the software environment for your websites. What's more, Debian performs really well on any hardware, as it is light and efficient and does not require much memory.