Debian is a well-known Linux release, that is used mainly on desktop computers, however a lot of people have started using it lately as a web server OS 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 numerous qualified volunteers all around the world, therefore any patch that is necessary to fix some issue is released within a few days. The same community will also help with any question or issue that a user may ever encounter, as they can be contacted via e-mail using e-mail lists and a qualified response will be sent in around 15-20 min. The advantage here is that all of your questions will be addressed by the same people who have designed 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 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 readily available for it.