Debian is a widespread Linux distribution, which is used mainly on desktop machines, but many people have started 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, therefore any patch that is necessary to fix a certain issue is released in a few days. The very same community will also help with any question or issue that a user may ever have, because they can be contacted through e-mail using mailing lists and a qualified response will be sent in around 15-20 minutes. The advantage here is that all of your queries will be addressed by the same people who have created the Operating System itself and they have an in-depth knowledge of how it functions. As Debian is provided for free, you will not need to pay any 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 readily available for it.