Debian is a widespread Linux distribution, that's 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 provides. The latter is a direct result the fact that Debian is developed and supported by countless qualified volunteers around the globe, therefore any patch which is needed to fix a particular issue is released within a matter of days. The same community will also help with any question or issue that a user may ever encounter, due to the fact that 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 questions will be addressed by the same people who have designed the Operating System itself and they have a detailed knowledge of how it works. As Debian is free, you won't have to pay any license fees to use it and you'll be able to customize it as much as you want or need. This is valid for the Operating System and the 30.000+ software packages which are available for it.