Debian is a well-known Linux distribution, which is used mainly on PC's, however numerous 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 consequence of the fact that Debian is developed and supported by a large number of qualified volunteers internationally, which means that any patch that's needed to fix a particular issue is released within a matter of days. The very same community will also help with any question or trouble which a user may ever encounter, as they can be contacted through e-mail using mailing lists and a qualified response will be sent in no more than 15-20 minutes. The advantage here is that all your queries will be replied by the same people who have created the Operating System itself and they have a detailed knowledge of how it works. As Debian is provided for free, you won't have to pay any kind of 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 readily available for it.