If you get a server of your own, it will run independently, so it will 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. Although keeping the Operating System updated is not always considered a necessity, it can be a really important task for a variety of reasons. A newer Operating system version may have better support for certain hardware, so you could get better performance for the sites and web applications which you install. Your server will also be more protected as updates typically include security patches that resolve small issues which may enable unauthorized individuals to access your content. Last, but not least, more recent script versions, which are also released for both improved security and for additional features, may need a later version of the Operating System in order to work correctly and with their full capabilities.