Debian is a Linux distribution, that's widespread for desktop computers, but it has been becoming more popular as a server Operating System over the last few years as well. It's really dependable and risk-free, as fixes are released in a couple of days after an issue is discovered. Debian has a large support community, so if you have any kind of questions or troubles with the OS or with any of the 30,000+ packages it comes with, you are able to contact the developers immediately through e-mail using special mailing lists and receive a reply within 15-20 min. The Debian community provides the best level of support possible, since all of your questions will be handled by exactly the same people who built Debian in the first place, so they have an exhaustive knowledge of how their system works. Since the Operating System is free to use and distribute, no license charges will be included with your hosting fees and you'll be able to change the program code files and any other software which you install without any restrictions, in order to optimize the software environment for your web sites. In addition, Debian performs very well on any hardware, because it is light and efficient and doesn't need a lot of memory.