If you get a hosting server of your own, it will work independently, so it will have its own Os and you can later install server side applications directly or script-driven sites through a hosting Control Panel. Even though keeping the Operating System updated isn't always considered a necessity, it can be a quite important task for a variety of reasons. A more modern OS version might have better support for certain hardware, so you might get better performance for the internet sites and web applications you install. Your server shall also be more secure because updates often include security patches that fix small problems that may permit unauthorized individuals to access your content. Last, but not least, newer script versions, which are also released for both increased security and for additional features, might require a later version of the Operating System in order to work effectively and with their full capabilities.