Debian is a widespread Linux distribution, which is used primarily on desktop machines, still numerous people have begun using it lately as a web server OS too, because of the stability and protection it offers. The latter is a direct result the fact that Debian is developed and supported by countless qualified volunteers internationally, which means that any patch that is needed to fix some issue is released in a couple of days. The same community can also help you with any question or problem which a user may ever experience, since they can be contacted through e-mail using e-mail lists and a qualified response will be sent in around 15-20 min. The advantage here is that all your questions will be addressed by the same people who have created 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 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 both the Operating System as well as the 30.000+ software packages that are available for it.