Debian is an OS that uses the Linux kernel. Although it is usually set up on personal computers, it is being used on an increasing number of web servers as well. The reason is that it's really stable, so a server running it will not have to be restarted for months. Debian is also regarded as being one of the most risk-free Operating Systems to choose from, since security patches are released within days after a problem is found. This is possible because thousands of skilled developers are part of the Debian project on a voluntary basis and not only do they work on the OS itself, they also provide 24/7 support by using special mailing lists and respond within 20 min to any kind of question. In this light, you'll have top-notch support directly from the developers who know their own platform in detail, and not from a third-party support team. Debian is also one of the Linux releases with the highest number of packages - over 30,000. Since the Operating System is free to use, you are able to modify both the core and all of the packages in any way you see fit. In addition, you will not need to pay any license fees.