Debian is a popular Linux distribution, that's used mainly on desktop machines, but lots of people have started using it lately as a web server Operating System as well, due to the stability and security it supplies. The latter is a result of the fact that Debian is developed and supported by a large number of qualified volunteers internationally, so that any patch that is required to fix a certain issue is released within a couple of days. The very same community can also help 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 competent response will be sent in around 15-20 minutes. The advantage here is that all of your queries will be replied by the same people who have made the Operating System itself and they have an in-depth knowledge of how it functions. As Debian is absolutely free, you will not need to pay any license fees to use it and you can customize it as much as you want or need. This is valid for the Operating System and the 30.000+ software packages that are available for it.