If you get a server of your own, it will operate independently, so it will have its own Os and you can later install server side apps directly or script-driven sites through a hosting Control Panel. Although keeping the Operating System updated is not always considered fundamental, it can be a rather important task for a number of reasons. A newer Operating system version may have better support for specific hardware, so you might get better performance for the internet sites and web apps that you install. Your server shall also be more protected since updates usually include security patches which deal with small problems which may allow unauthorized people to access your content. Last, but not least, more recent script versions, which are also released for both boosted security and for additional features, may require a later version of the Operating System in order to work correctly and with their full capabilities.