If you get a server of your own, it will operate independently, so it'll have its own Os and you'll be able to later install server side programs directly or script-driven sites via a hosting Control Panel. While keeping the Os updated is not always considered fundamental, it can be a really important task for several reasons. A newer OS version might have better support for specific hardware, so you may get better performance for the internet sites and web apps you install. Your server shall also be more safe since updates normally include security patches which resolve small problems that may permit unauthorized individuals to access your content. Last, but not least, current script versions, which are also released for both increased security and for additional features, may need a later version of the Os in order to work correctly and with their full capabilities.