If you get a server of your own, it will run independently, so it will have its own Operating System and you could later install server side applications directly or script-driven sites via a hosting Control Panel. Even though keeping the Os updated isn't always considered a necessity, it can be a really important task for a variety of reasons. A more modern Operating system version may have better support for specific hardware, so you might get better performance for the websites and web apps which you install. Your server will also be more safe as updates typically include security patches that fix small issues that may permit unauthorized individuals to access your content. Last, but not least, more modern script versions, which are also released for both enhanced security and for additional features, may need a later version of the Operating System in order to work effectively and with their 100 % capabilities.