Debian is a well-known Linux distribution, that is used primarily on PC's, but a lot of people have begun using it lately as a web server OS as well, due to the stability and protection it offers. The latter is a consequence of the fact that Debian is developed and supported by numerous qualified volunteers internationally, so any patch that's necessary to fix some issue is released within a couple of days. The very same community can also help with any question or problem that a user may ever have, due to the fact that they can be contacted through e-mail using mailing lists and a competent response will be sent in no more than 15-20 minutes. The advantage here is that your questions will be answered by the same people who have made the Operating System itself and they have an in-depth knowledge of how it functions. As Debian is absolutely free, you will not have to pay any license fees to use it and you can customize it as much as you want or need. This is valid for both the Operating System and the 30.000+ software packages which are available for it.