Debian is an Operating System that uses the Linux kernel. Although it is usually set up on personal computers, it is being used on more and more web servers as well. The reason is that it is really stable, so a server running it won't need to be restarted for months. Debian is also considered to be among the most secure Operating Systems you can get, due to the fact that security patches are released within days after a problem is found. This is possible because thousands of skilled developers are employed by the Debian project on a voluntary basis and not only do they work on the OS itself, they also provide 24/7 support through special mailing lists and respond within 20 minutes to any question. In this light, you'll enjoy 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 among the Linux releases with the highest number of packages - over 30,000. Since the Operating System is absolutely free to use, you will be able to modify both the core as well as all the packages in any way you see fit. Furthermore, you will not need to pay any kind of license fees.