Debian is a Linux distribution, that's widespread for desktop computers, however it's been becoming more popular as a server OS during the last couple of years as well. It is very dependable and secure, since fixes are released within a couple of days after a problem is discovered. Debian has a large support community, so when you have any questions or issues with the OS or with any of the 30,000+ packages it features, you are able to contact the developers without delay via email using special e-mail lists and receive a reply in 15-20 minutes. The Debian community gives you the top level of support possible, because 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 own system operates. Since the Operating System is 100% free to use and distribute, no license costs will be included with your web hosting fees and you will be able to modify the code files and any additional software which you install without restrictions, in order to optimize the software environment for your sites. Furthermore, Debian performs really well on any hardware, because it's light and efficient and does not require a lot of memory.