Debian is an Operating System which uses the Linux kernel. Even though it is usually installed on personal computers, it's being used on more and more web servers as well. The reason is that it's very stable, so a server running it will not need to be restarted for months. Debian is also considered to be among the most protected Operating Systems in existence, due to the fact that security patches are released within days after an issue is found. This is possible since thousands of qualified developers are employed by the Debian project on a voluntary basis and not only do they work on the OS itself, but they also provide 24/7 support through special e-mail lists and reply within 20 minutes to any kind of question. In this light, you will get 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 among the Linux releases with the highest number of packages - more than 30,000. Since the Operating System is absolutely free to use, you can modify both the core as well as all of the packages in any way you see fit. Also, you won't be required to pay any kind of license fees.