Debian is a popular Linux distribution, that's used mainly on desktop machines, however numerous people have started using it lately as a web server Operating System as well, due to the stability and security it provides. The latter is a consequence of the fact that Debian is developed and supported by thousands of qualified volunteers worldwide, so any patch which is needed to fix some issue is released in a matter of days. The same community can also help you with any question or issue that a user may ever encounter, because they can be contacted via electronic mail using e-mail lists and a competent response will be sent in around 15-20 minutes. The advantage here is that all your queries 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 functions. As Debian is free, you will not need to pay any license fees to use it and you can customize 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.