Debian is an Operating System that uses the Linux kernel. Although it is usually installed on desktop machines, it is being used on a growing number of web servers as well. The reason is that it's really stable, so a server running it won't need to be restarted for months. Debian is also considered to be among the most protected Operating Systems nowadays, as security patches are released within days after a problem is found. This is possible since thousands of well-experienced 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 reply within 20 min to any kind of question. In this light, 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. As the Operating System is absolutely free to use, you are able to modify both the core and all the packages in the way you see fit. In addition, you won't be required to pay any license fees.