Every virtual or dedicated hosting server has its own Os and operates independently from the hosting machines of other clients. Updating the OS is usually overlooked, but doing that might have lots of advantages for your sites. The most important reason to use the most up-to-date version is that patches are typically released to repair security holes within the Operating System code, so if you don't install the updates, you risk individuals with harmful intentions to take advantage of these holes and to gain access to your content. Operating system updates are also released for much better efficiency of the system as a whole and for much better compatibility with the hardware on the market, which can directly influence the functionality of your sites. If the efficiency and the security of your scripts is the reason to update them, you could also know that their most recent versions require an updated Os so as to work properly, consequently keeping the Operating system up-to-date is always a wise idea.