Debian is a Linux distribution, which is widespread for desktop machines, yet it's been gaining in popularity as a server OS during the last few years as well. It's really stable and secure, since fixes are released within a couple of days after an issue is discovered. Debian has a huge support community, so if you have any questions or troubles with the OS or with some of the 30,000+ packages it features, you are able to contact the developers right away through electronic mail using special e-mail lists and receive a response within 15-20 minutes. The Debian community offers the best level of support possible, since all your questions will be handled by the very same people who built Debian in the first place, so they have an exhaustive knowledge of how their system functions. Since the Operating System is absolutely free to use and distribute, no license charges will be included with your web hosting fees and you will be able to modify the code files and any additional software that you install without restrictions, in order to optimize the software environment for your sites. What's more, Debian performs very well on any hardware, as it is light and fast and doesn't need much memory.