Debian is a popular Linux distribution, that is used mainly on desktop machines, still many people have begun using it lately as a web server Operating System as well, due to the stability and protection it supplies. The latter is a direct result the fact that Debian is developed and supported by thousands of qualified volunteers internationally, so any patch which is required to fix some issue is released in a matter of days. The same community will also help with any question or trouble that a user may ever encounter, because they can be contacted via email using e-mail lists and a qualified response will be sent in around 15-20 minutes. The advantage here is that all of your queries will be replied by the same people who have made the Operating System itself and they have a detailed knowledge of how it works. As Debian is absolutely free, you won't need to pay any kind of license fees to use it and you will be able to 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.