If you get a server of your own, it will run independently, so it'll have its own Os and you could later install server side applications directly or script-driven sites through a hosting Cp. Although keeping the Os updated isn't always considered fundamental, it can be a very important task for several reasons. A newer Operating system version could have better support for certain hardware, so you could get better performance for the internet sites and web applications you install. Your server shall also be more protected since updates often include security patches that take care of small issues which may enable unauthorized people to access your content. Last, but not least, current script versions, which are also released for both improved security and for additional features, might require a later version of the Operating System in order to work properly and with their 100 % capabilities.