Debian is an Operating System that uses the Linux kernel. Though it is usually set up on desktops, it's being used on an increasing number of web servers as well. The reason is that it's really stable, so a server running it won't have to be restarted for months. Debian is also regarded as being among the most risk-free Operating Systems nowadays, since security patches are released within days after an issue is found. This is possible since thousands of experienced 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 by using special mailing lists and respond within twenty minutes to any question. Thus, you will obtain 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 one of several Linux releases with the highest number of packages - over 30,000. Since the Operating System is completely free to use, you will be able to modify both the core as well as all the packages in the way you see fit. Furthermore, you won't be required to pay any license fees.