Debian is an OS which uses the Linux kernel. Though it is usually installed on desktops, it is being used on an increasing number of web servers too. The reason is that it is very 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 to choose from, as security patches are released within days after a problem is discovered. This is possible because 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 by using special e-mail lists and respond within twenty minutes to any question. Thus, you'll obtain an outstanding level of 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 costs nothing to use, you're able to modify both the core as well as any of the packages in the way you see fit. Also, you will not have to pay any kind of license fees.