Debian is a preferred Linux distribution, that's used mainly on desktop machines, however many people have begun using it lately as a web server OS as well, because of the stability and protection it supplies. The latter is a result of the fact that Debian is developed and supported by numerous qualified volunteers worldwide, therefore any patch which is necessary to fix a certain issue is released in a few days. The same community will also help you with any question or trouble which a user may ever have, since they can be contacted through e-mail using mailing lists and a competent response will be sent in around 15-20 minutes. The advantage here is that all your questions will be responded to by the same people who have developed the Operating System itself and they have an in-depth knowledge of how it works. As Debian is free, you won't need to pay any license fees to use it and you can personalize it as much as you want or need. This is valid for the Operating System and the 30.000+ software packages that are available for it.