Debian is a Linux distribution, which is widely used for desktop computers, but it has been gaining popularity as a server OS over the last few years too. It's really stable and risk-free, as fixes are released within a few days after an issue is discovered. Debian has a vast support community, so when you have any questions or troubles with the OS or with any of the 30,000+ packages it features, you will be able to contact the developers straight away through electronic mail using special e-mail lists and receive a reply in 15-20 min. The Debian community offers the top level of support possible, because all of your questions will be handled by the same people who created Debian in the first place, so they have an in-depth knowledge of how their system operates. Because the Operating System is 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 other software which you install without restrictions, to optimize the software environment for your sites. In addition, Debian performs very well on any kind of hardware, as it's light and effective and does not require a lot of memory.