Each and every virtual or dedicated hosting server has its own Operating System and operates independently from the hosting servers of other clients. Updating the Operating system is usually ignored, but doing that may have a wide range of advantages for your sites. The most important reason to use the latest version is that patches are usually released to repair security holes within the Operating System code, so if you don't install the updates, you risk people with malicious intentions to take advantage of these holes and to access your content. Operating system updates are also released for improved efficiency of the system overall and for much better compatibility with the hardware available on the market, which can immediately affect the performance of your websites. If the performance and the security of your scripts is the reason to update them, you might also find out that their most recent versions require an updated Os so as to function properly, so keeping the OS up-to-date is always recommended.