If you get a hosting server of your own, it will operate independently, so it'll have its own Operating System and you can later install server side applications directly or script-driven websites through a hosting Control Panel. While keeping the Os updated is not always considered fundamental, it can be a rather important task for several reasons. A newer OS version may have better support for specific hardware, so you might get better performance for the sites and web applications you install. Your server will also be more safe because updates normally include security patches that resolve small issues that may allow unauthorized people to access your content. Last, but not least, current 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 correctly and with their 100 % capabilities.