Debian is an Operating System that uses the Linux kernel. Even though it is usually installed on desktop machines, it's being used on an increasing number of web servers as well. The reason is that it is very stable, so a server running it won't have to be restarted for months. Debian is also regarded as being among the most safe Operating Systems nowadays, because security patches are released within days after a problem is found. This is possible since thousands of skilled 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 by using special mailing lists and respond in twenty minutes to any kind of question. In this light, you will receive 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 one of the Linux releases with the highest number of packages - more than 30,000. Since the Operating System costs nothing to use, you will be able to modify both the core as well as any of the packages in any way you see fit. In addition, you will not have to pay any kind of license fees.