Each virtual or dedicated hosting server has its own Operating System and functions independently from the hosting machines of other clients. Updating the Operating system is frequently ignored, but doing that could have lots of benefits for your sites. The most significant reason to use the most recent 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 individuals with harmful intentions to use these holes and to get access to your content. OS updates are also released for much better functionality of the system as a whole and for better compatibility with the hardware on the market, which could directly affect the performance of your websites. If the functionality and the security of your scripts is the reason to update them, you might also find out that their latest versions require an updated Os to be able to work properly, therefore keeping the OS up-to-date is always wise.