Debian is an Operating System that uses the Linux kernel. Though it is usually set up on desktops, it's being used on a growing number of web servers too. The reason is that it is very stable, so a server running it will not have to be restarted for months. Debian is also considered to be among the most protected Operating Systems in existence, as security patches are released within days after an issue is found. This is possible since thousands of qualified developers are working for the Debian project on a voluntary basis and not only do they work on the OS itself, in addition, they provide 24/7 support via special mailing lists and respond within 20 minutes to any question. Thus, you will obtain top-notch support directly from the developers who know their own platform in depth, and not from a third-party support team. Debian is also one of the Linux distributions with the highest number of packages - over 30,000. Since the Operating System costs nothing to use, you're able to modify both the core and all of the packages in any way you see fit. Furthermore, you won't need to pay any license fees.