Debian is a widespread Linux release, that is used primarily on PC's, still lots of people have started using it lately as a web server Operating System as well, due to the stability and security it offers. The latter is a direct result the fact that Debian is developed and supported by countless qualified volunteers internationally, so any patch that's required to fix a particular issue is released within a couple of days. The same community can also help with any question or issue that a user may ever encounter, as they can be contacted via email using e-mail lists and a qualified response will be sent in no more than 15-20 min. The advantage here is that all your questions will be addressed by the same people who have made the Operating System itself and they have a detailed knowledge of how it works. As Debian is free, you will not need to pay any kind of license fees to use it and you can personalize it as much as you want or need. This is valid for both the Operating System and the 30.000+ software packages that are available for it.