Debian is an OS that uses the Linux kernel. Though it is usually installed on desktop computers, it's being used on more and more web servers too. The reason is that it's very stable, so a server running it won't need to be restarted for months. Debian is also considered to be one of the most risk-free Operating Systems you can get, as security patches are released within days after a problem is found. This is possible since thousands of well-trained developers work for the Debian project on a voluntary basis and not only do they work on the OS itself, but they also provide 24/7 support via special mailing lists and respond within 20 min to any question. Thus, you will enjoy top-level support directly from the developers who know their own platform in detail, and not from a third-party support team. Debian is also among the Linux releases with the highest number of packages - more than 30,000. Since the Operating System is free to use, you are able to modify both the core as well as all of the packages in the way you see fit. Furthermore, you will not be required to pay any kind of license fees.