Debian is an Operating System that uses the Linux kernel. Though it is usually set up on personal computers, it's being used on an increasing number of web servers too. The reason is that it is really stable, so a server running it will not have to be restarted for months. Debian is also considered to be one of the most risk-free Operating Systems to choose from, due to the fact that security patches are released within days after a problem is found. This is possible since thousands of experienced developers are employed by 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 e-mail lists and reply within 20 min to any question. Thus, you'll have top-level support directly from the developers who know their own platform in depth, and not from a third-party support team. Debian is also among the Linux distributions with the highest number of packages - over 30,000. As the Operating System is absolutely free to use, you're able to modify both the core as well as all the packages in the way you see fit. Also, you will not need to pay any license fees.