Debian is a well-known Linux distribution, that is used mainly on personal computers, but lots of people have begun using it lately as a web server OS as well, because of the stability and protection it provides. The latter is a consequence of the fact that Debian is developed and supported by a large number of qualified volunteers internationally, which means that any patch which is necessary to fix a certain issue is released in a couple of days. The very same community can also help with any question or trouble that a user may ever have, due to the fact that they can be contacted via e-mail using e-mail lists and a competent response will be sent in no more than 15-20 minutes. The advantage here is that all your questions will be addressed by the same people who have made the Operating System itself and they have a detailed knowledge of how it works. As Debian is provided for free, you will not have to pay any kind of license fees to use it and you can customize it as much as you want or need. This is valid for the Operating System as well as the 30.000+ software packages that are readily available for it.