Debian is an Operating System which uses the Linux kernel. Even though it is usually installed on desktop computers, it's being used on more and more web servers too. The reason is that it is really stable, so a server running it won't need to be restarted for months. Debian is also regarded as being among the most protected Operating Systems in existence, since security patches are released within days after an issue is discovered. This is possible since thousands of well-trained 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 through special mailing lists and reply within 20 minutes to any kind of question. In this light, you'll 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 several Linux distributions with the highest number of packages - over 30,000. Since the Operating System costs nothing to use, you will be able to modify both the core as well as all of the packages in the way you see fit. In addition, you will not be required to pay any kind of license fees.