Debian is a Linux distribution, that is preffered for desktop machines, but it's been becoming more popular as a server OS over the last couple of years as well. It's really dependable and safe, as fixes are released within a few days after a problem is discovered. Debian has a vast support community, so when you have any kind of questions or problems with the OS or with some of the 30,000+ packages it is equipped with, you'll be able to contact the developers without delay via email using special e-mail lists and receive a response in just 15-20 minutes. The Debian community gives you the best level of support possible, as all of your questions will be handled by the very same people that built Debian in the first place, so they have a detailed knowledge of how their own system functions. As the Operating System is free to use and distribute, no license charges will be included with your hosting fees and you will be able to modify the program code files and any other software that you install with no restrictions, to optimize the software environment for your web sites. In addition, Debian performs really well on any kind of hardware, because it is light and quick and doesn't require much memory.