Debian is an Operating System which uses the Linux kernel. Even though it is usually set up on desktops, it's being used on a growing number of web servers too. The reason is that it is really stable, so a server running it won't need to be restarted for months. Debian is also considered to be among the most safe Operating Systems to choose from, because security patches are released within days after an issue is found. This is possible because thousands of skilled developers work for 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 reply in twenty minutes to any kind of question. Thus, you'll enjoy an outstanding level of support directly from the developers who know their own platform in depth, and not from a third-party support team. Debian is also one of the Linux releases with the highest number of packages - over 30,000. Since the Operating System is absolutely free to use, you can modify both the core as well as any of the packages in any way you see fit. Also, you will not need to pay any kind of license fees.