Debian is an OS that uses the Linux kernel. Though it is usually set up on personal computers, it is being used on more and more web servers too. The reason is that it's really stable, so a server running it will not have to be restarted for months. Debian is also regarded as being one of the most safe Operating Systems available, as security patches are released within days after a problem is found. This is possible since thousands of well-experienced developers are part of 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 minutes to any 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 among the Linux releases with the highest number of packages - more than 30,000. As the Operating System costs nothing to use, you can modify both the core and any of the packages in the way you see fit. Also, you won't be required to pay any kind of license fees.