If you get a server of your own, it will work independently, so it'll have its own Os and you'll be able to later install server side programs directly or script-driven websites through a hosting Cp. Even though keeping the Os updated isn't always considered an absolute necessity, it can be a rather important task for a variety of reasons. A more modern OS version might have better support for specific hardware, so you might get better performance for the websites and web applications that you install. Your server will also be more protected as updates normally include security patches that deal with small issues that may enable unauthorized people to access your content. Last, but not least, newer script versions, which are also released for both enhanced security and for additional features, may require a later version of the Operating System in order to work correctly and with their 100 % capabilities.