Debian is a popular Linux distribution, that is used primarily on PC's, but many people have begun using it lately as a web server Operating System too, due to the stability and protection it supplies. The latter is a direct result the fact that Debian is developed and supported by numerous qualified volunteers around the globe, so that any patch that is necessary to fix some issue is released within a few days. The very same community will also help you with any question or problem which a user may ever experience, since they can be contacted via email using e-mail lists and a competent response will be sent in around 15-20 minutes. The advantage here is that all of your questions will be responded to by the same people who have designed the Operating System itself and they have a detailed knowledge of how it functions. As Debian is absolutely free, you won't 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 both the Operating System and the 30.000+ software packages which are readily available for it.