Debian is a well-known Linux distribution, that's used primarily on desktop computers, still numerous people have started using it lately as a web server Operating System as well, because of the stability and protection it offers. The latter is a result of the fact that Debian is developed and supported by a large number of qualified volunteers all around the world, which means that any patch that is required to fix a particular issue is released in a matter of days. The same community can also help with any question or issue that a user may ever experience, as they can be contacted through email using mailing 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 answered by the same people who have created the Operating System itself and they have an in-depth knowledge of how it works. As Debian is free, you won't 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 as well as the 30.000+ software packages which are readily available for it.