Debian is a preferred Linux release, that's used primarily on PC's, but a lot of people have started using it lately as a web server OS as well, because of the stability and protection it supplies. The latter is a direct result the fact that Debian is developed and supported by countless qualified volunteers all around the world, so that any patch that is necessary to fix a particular issue is released within a couple of days. The same community can also help with any question or problem which a user may ever have, because they can be contacted via e-mail using mailing lists and a qualified response will be sent in around 15-20 min. The advantage here is that your queries will be answered by the same people who have created the Operating System itself and they have a detailed knowledge of how it works. As Debian is absolutely free, you will not need to pay any kind of license fees to use it and you will be able to customize it as much as you want or need. This is valid for the Operating System as well as the 30.000+ software packages which are available for it.