Debian is an Operating System which uses the Linux kernel. Even though it is usually set up on desktop machines, it's being used on more and more web servers as well. The reason is that it is really stable, so a server running it will not have to be restarted for months. Debian is also regarded as being among the most protected Operating Systems you can get, because security patches are released within days after an issue 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, in addition, they provide 24/7 support by using special e-mail lists and reply in twenty minutes to any kind of question. Thus, you will get 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 several Linux releases with the highest number of packages - over 30,000. As the Operating System is free to use, you're able to modify both the core as well as any of the packages in any way you see fit. In addition, you will not be required to pay any kind of license fees.